Do Native Speakers Ever Use These Rare English Words?

In literature yes, day to day no.

I know what lachrymose & sacrosanctity mean so I’ll speak on those, tho the other words I could probably guess. Lachrymose I would only use in literary writing, or in very specific types of speech, ie a poetry lecture or something. Using that in normal speech would come off very pretentious. Sacrosanctity has specific meaning in religious contexts so I could see myself using that if it was relevant in a conversation about religion. It doesn’t have any synonyms in that context, so it would be totally appropriate. In casual conversation unrelated to religion, again it would be very marked and odd. As far as remembering those words, I’d probably look up their etymologies and learn what their parts mean. An intuitive understanding of those parts can help you build lots of words together and “guess” when you see them in context.

The kind of words that would appear in an American SAT exam or perhaps a Spelling Bee but not in typical everyday conversation unless people were trying to flex their level of education (and implied intelligence) via their vocabulary. 

I might occasionally use these words in writing but I would not speak these words. 

I teach English at the high school level and I have never used any of these in normal conversation. I’ve only ever seen a few of them used, and mostly in older, classical literature.

I use some. Propitiatory only in a religion setting, but I do use perspicacious and sacrosanct. Lachrymose I understand, but wouldn't say.

No, and people who do in day-to-day conversation are often viewed negatively (pretentious, even condescending). Since very few people use or know them they aren't very useful in regular conversation.   You can't communicate your point very well with words that other people don't understand. In professional or academic writing you can use more uncommon words, but the ones that are used tend to be field specific, and not like the ones you listed. It really seems like a waste of your time to memorize words like that. Edit: I have heard and read "sacrosanct" plenty of times, but not in regular conversation.  It's the kind of word you come across in NPR reporting.

I am a native speaker and would not use any of these words regularly. I've used "sacrosanct" (but not "sacrosanctity"), but I have to admit that I wasn't even 100% sure what the rest meant. But, a lot of them share roots with words I do know and use more often. When I was in high school, it was common for kids to learn less common words in preparation for college entrance tests like the SAT. The key to that wasn't memorizing all the words so much as learning some common roots to make it easier to guess at the meaning of less common words. I studied Latin in high school, and that helped a lot with guessing. So, rather than focus on memorizing these words, I'd take a look at their roots, start learning those, and start looking for patterns.

These are all words that you might find in literature from probably the 19th century or before. "Sacrosanct" is a word you might actually use, and I think most would immediately understand "sacrosanctity," but that that's it.

I would use most of them occasionally- but then I am sometimes quite an unbearable ponce.

I know and have used perspicacious, lachrymose and propinquity. Have never come across the other three words, though I can guess what sacrosanctity means from the word sacrosanct, which is not so uncommon. I’m a UK native speaker with an MA in English.

I learned "perspicacious" in 8th grade English class, but have never used it. I have never encountered the second or third words. I have never used any of these words in writing or speech, though I may occasionally use "sacrosanct" and I have encountered "propinquity" and "lachrymose" a handful of times in my life. I can guess that "lachrymose" has something to do with tears or weeping. Safe to say, none of these are everyday words, though "sacrosanct" (not "sacrosanctity"!) is relatively common.

The overwhelming majority of native speakers will go their entire lives without ever saying these words or knowing what they mean.

I’ve heard these words but don’t think I’ve ever personally used them in speech. But oh man what a flashback to learning the word lachrymose from Lake Lachrymose in Series of Unfortunate Events. That series taught some cool words!

Sacrosanctity sure, common enough in its sacrosanct form. I know lachrymose, but I’m reasonably sure if I used it only a few would understand what I meant. The others I have never heard used.

No. Sacrosanct maybe but these are not, amongst the general populace, common everyday words.

Never heard of those words and definitely don’t use them

I can deduce what most of these words mean because my native language is Latin-derived, as are these words. If I was a native English speaker that would certainly not be the case, though.

Of those, the only ones I've ever encountered are propitiatory and sacrosanct (the adjective form of sacrosanctity).

Sacrosanctity is the most familiar to me.

I'm a native English speaker from the UK. These words are not common but they are all in my lexicon (there's another candidate for your list); none of them would send me scurrying for the dictionary if I encountered them, and I might use them myself on occasion (in fact I think it was only yesterday that I told a young man that I was impressed by his perspicacity - I remember because he asked me what it meant). I don't have any particular advice on how to learn these words, but I read a lot of books and that may help. And if I encounter a word I don't know, I've made it a strict rule, ever since I was a teenager (I'm now 69), to look it up. Obviously one can readily get by in English without words like these; but I'm afraid the answer to your question is that an educated English speaker would be expected at least to understand these words, and probably also to use them occasionally.

No none of those. I’ve probably used “sacrosanct” but never “sacrosancticity”, which my spellcheck doesn’t even recognize. The other words I have never used once in my life. I would say there’s no need to make efforts to memorize these words. The once or twice that you encounter them will be written and you can just use a dictionary. They are effectively irrelevant to fluency in English.

In daily life, no. But several of these words have technical meanings in theology and philosophy, and so would be seen in thise kinds of works.

Not really. The closest would be variations, like "sacrosanct" and "sanctity". On another aspect of your post, do not learn loads of vocabulary for the sake of it. As you can see, you are trying to learn words that even native speakers rarely use. You won't use them, unless you deliberately try, which is often inappropriate for the time. You will have people not really understanding or wondering why you are using such fancy words when there are simpler ones to use. Speaking English well does not mean having to use really fancy or unusual words. It won't sound natural. Learn vocabulary for things you do talk about and want to be able to talk about. You will remember words that you use regularly. Your vocabulary will naturally grow as you talk more and hear words that other people use when talking. That is a better way to learn vocabulary and remember it than just going through a list of words.

I encounter a couple of these words occasionally when I read but I have never used any of them. Have never encountered perspicuous, propitiatory, or propinquity, not even once. I have seen sacrosanct and sanctity, but not sacrosanctity.

I live in the United State and I can’t even pronounce most of those. They are not common here.

I think most native speakers would Look at you sideways if you used most of those words.

I've never heard any of these used outside of poetry or prose. Basically the only times they're used is when someone is trying to sound extra fancy/dramatic.

I have probably only ever used two of them: perspicacious and sacrosanct. And those only two or three times each in my whole life.

In the context of a casual conversation where you're trying to express something perfectly ordinary, most of these would be somewhere between "confusing" and "that's the most pretentious shit I've ever heard" on the less-than-ideal-expression scale. The most likely use for any of these outside of a specific academic context, in my opinion, is at least slightly sarcastic. For example: "Oh, sorry Jake, didn't mean to violate the sacrosanctity of your coffee mug with my hot chocolate." They're definitely fun vocabulary, though. Probably not bad choices to practice English pronunciation rules, either.

Perspicacious, perspicuous, propitiatory, and propinquity no. I don't think I've ever heard of these and I'm occasionally complemented on my vocabulary. Lachrymose and sacrosanctity I've heard of before, but they are extremely rare!

Don't

Nope we don't use them often at all.

I have used "Propinquity" but only ever when I was teaching my Grandmother that the word "propinquity" is real, and I only know it because I was studying relationships. The word "Promiscuity" is sometimes used to talk about people sleeping with lots of people. The rest are words I have never seen used.

I learned those words in high school. I never use them and I never hear them used. It would be very hard for me to use them in a way that felt natural.

Those are used in writing, and I've used "perspicacious" in actual speech because it's hilarious to me to say "How very perspicacious of you" instead of "No shit, Sherlock". Sacrosanct is also reasonably common, though sacrosanctity is a little less so. I've certainly used propitiatory and lachrymose in writing fiction, but not in common correspondence. The best advice i have is terrible advice. 😅 I remember the meanings of those words because I've learned enough Latin and Greek to recognize the roots. Like, lachrymose comes from Latin lacrima, tears. In anatomy, tears are produced in the lacrimal gland, and stored in the lacrimal pouch in the corner of your eyes. The more words you learn, the more you'll start to recognize these patterns. I know it's cold comfort when it feels like you have to memorize a lot of gibberish, but it'll happen, I promise!

I’ve used a few of them, not in everyday English, though. Perspicuous probably most frequently. You have a couple of words in unusual forms: Sacrosanct (adj) is more frequent than the noun. Lachrymal (adj) is used in anatomy / biology - the lachrymal glands. Perhaps you should consider studying how to transform words, adjective - noun / verb - adjective and noun. It would help you retain the meaning of some of these words (through a levels of processing approach) and help you to work out the likely meaning of any new words you come across (in addition to using contextual clues) by looking at the root of the word - eg propinquity.

in my daily life, I honestly just mostly use first-grader words and swear words in my professional life, I wouldn't even use those because what's the point, to prove you went to college? they're rare for a reason, and mostly that reason is that they don't say anything special that a simpler word cannot say the more unique or nuanced the meaning, the more likely they are to be in use the best way to remember them in my experience is to focus on the ones that are not obvious from the root word or from your knowledge of other languages (those you can remember by association so work off that) then flashcard the ones that seem standalone and unrelated to previous knowledge

I'd use lachrymose in relation to music or books that are designed to tug at your heartstrings, and do it in a heavy-handed way Perspicacious is occasionally used, but I wouldn't. The others? Nah

I do use a lot of (what my friends call) 10-dollar words, but only when really no other word works. E.g. "serendipitous" is in my active vocabulary, and I use it when appropriate. Of the words in thy questioun I've never used any of those but anyway....

I did use perspicacious last Tuesday, but in writing. We wouldn’t say those words in an everyday conversation. The only way I can think of to remember them better is to study Greek and Latin: if you remember *hinc illae lacrimae*, you’ll remember that lachrymose means tearful. French is good too. Most fancy words in English come from one or all of those three languages. That’s not actually easier, though. Next-best is recognizing the same roots in multiple words, such as perspective and conspicuous reminding you that perspicuous literally is “for being see-able”.

Ive never heard of any of these lol what are the meanings? Born and raised in the US The average everyday person, will almost never use these words. You WILL get a funny look. Maybe in some small highly educated circles, schools, english class, maybe. Maybe in an advanced literature class. But the avg person on the street will never.

I know them all, but use them only on special occasions.

None of those, no. The rarest words most speak are the ones we make up ourselves.

I'm well read and many of my hobbies are heavy on reading, so I can definitely imagine -encountering- some of these words. Perspicacious feels like the one I'd be most likely to use, but tbh I'd probably pronounce it wrong. I'd describe something as "sacrosanct" or having "sanctity" before I'd use "sacrosanctity." "Lacrymosal essence" sounds like the sort of overly-flowery phrasing I might use for comical/exaggerated rhetorical effect. Pretty sure I've actually said this before. I think coming up with sentences that use the word in a way that helps me remember the definition is how I'd be most likely to learn vocabulary. Probably my favorite extremely-rarely-used word is "piacular," after the time I attended a pagan ritual and the organizers opened proceedings with an offering of piacular bacon, as a pre-emptive apology for any wrongs or or insults they might give the roman gods in the process.

Perspicacious/perspicacity is probably more well known than any of the others if only due to its use in a notable Simpson’s TV show reference [HERE](https://youtu.be/Vc0tMcabaA8?si=_Zgw31OJfAYsPp6C&utm_source=ZTQxO). I personally love to use obscure words and am an avid cryptic crossword solver. I also studied Latin in high school and classical civilizations in university. This helps to nasciently understand words like lachrymose from its root meanings. In my daily life I have used and still use, in routine conversations, words such as lachrymose, propinquity, and sacrosanctity. However, I would not be surprised by any English language native speaker not knowing these words. I have not personally used the remaining ones listed, that I can recall.

Not in my daily life. But they’re words that I know, because I’m a word person. P.S. All except “sacrosanctity.” I use sacrosanct relatively often, but I’ve never seen that form of the word before. Also, being pedantic isn’t what I do.

I’ve never heard any of those used irl

My son and I tell each other later when we have successfully work big words into normal conversations. The last one I was able to pull off was "presciently". I like words and often decide how eclectic my vocabulary will be based on the audience I'm addressing. None of your words would ever make the cut in real life. I think sacrosanct is the most normal root in your list. I've used lachrymose (as well as sanguine and melancholic) for fun, propitiation in religious conversations. And, of course, repeated Lisa Simpson's famous lament, "I'm losing my perspicacity!"

I use perspicacious when I’m sarcastically being erudite. The average American English speaker has an elementary vocabulary level. I read a lot and am familiar with this vocabulary, but wouldn’t use it in a casual conversation. Otherwise I just come off as a pompous intellectual.

Know them all, have probably used maybe one or two, once.

Those are words that someone might have to learn for the GRE (the exam one takes to place into graduate school) and then never hear again. As a native English speaker with a doctoral degree, I couldn't tell you what any of those words mean.

I have just enough Latin, French, and Middle English (only a little) that I can sometimes dope out the meaning of obscure words by identifying root words. If you are unfamiliar with a word, make it a habit to search for the etymology of that word. Then you have a little "story" of the word's life, and stories are easier to remember than simple facts. It's just how our brains work.

I use perspicacious and propinquity occasionally. Propinquity is one of my favorite words, it describes how I've met my closest friends. None of these are quotidian words though, and unless you know your audience well, using them will make you sound like a boor

I have never used these words in my life

a well-read english speaker will recognize all or most of these, but will probably not use them in day-to-day life.

I know all the words except “perspicuous,” but the only one I’ve used outside of a deliberate attempt to use a fancy word is “propitiatory” (as the appropriate jargon for a specific context). The simpler root “sacrosanct” gets some use, though. (Disproportionately but not exclusively with audiences for whom “propitiatory” is appropriate.)

I learned “perspicacious” in my linguistics studies and find it useful. But I wouldn’t expect a random person with a HS education to know it. “Perspicuous” is completely obscure. “Propitiate” is a normal enough verb, but I’ve never heard the adjective form. “Lachrymose” is something I’d understand if I read it in Victorian poetry, but way too ornate for ordinary use. Associations with the “lacrimosa” segment of the traditional Catholic requiem mass (and especially Mozart’s version). I’ve seen “propinquity” in old legal texts but need context to remember what it means. “Sacrosanct” is a normal adjective but its noun form is rare. If I wanted to use it as a noun in off-the-cuff speech, I’d just as likely land on “sacrosanctness.”

lachrymose is the only one i'd ever use

These are words you’ll see in books but it would be pretty rare to hear them in conversation Unless you’re C2 already, I would advise against spending much time on these. Even then, when talking about words this rare, it’s best to learn them as you find them.

These are the kinds of words you're likely to encounter in novels by authors who like to drop in rarely-used vocabulary once or twice per novel

I don't know any of those words.

The English language used to be a lot simpler. The problem is that England was taken over by a French-speaking dynasty of monarchs back in 1066 and as a result using "big words" (i.e. compounds formed from Latin/French roots) became a way to show prestige. This has had long-lasting effects, with the result being that when people want to sound educated, cultured, smart etc they use obscure Romance compounds in place of perfectly good English phrases. We raise cows but eat beef, we raise pigs but eat pork, and we randomly say "in lieu" rather than "instead". When you try to learn English vocabulary, after a certain point you're just learning French, Greek and Latin because most of the obscure vocab words are borrowed from those sources. "Sacrosanct" for example is a word that is arguably unnecessary, having multiple synonyms which are way more common, but you hear politicians and other public speakers use it all the time because it just sounds important.

Not unless i wanted to sound smarter and more arrogant than others. Even then if you don't want to sound like a know it all, you'd only use one overly complicated word in a conversation. Example: "the dale is verdant and the sky is azure, the scenery was of eden" Vs "the valley was very green and the sky was very blue, it looked like paradise."

Lachrymose is probably the only one of the words I've used before and even that one I've probably only ever used once or twice

I occasionally say the first but its more of a party trick than a serious attempt to communicate. The others, well i know what they mean but l don't recall using them.

 I’m not a native speaker, but I’ve also stumbled across some of these in books and just... why. Like, "perspicacious" sounds like a fancy way to say "perceptive," but I’ve never heard anyone actually say it out loud. I asked my native friend about this once, and she laughed and said half of these words are just for sounding smart in essays or impressing your professor. 😂 The only one I’ve seen somewhat often is "sacrosanct," usually in formal writing or debates. The rest? Pretty rare. For memorizing them, I try to link them to funny images or stories like "lachrymose" (tearful) makes me think of a lachrymose lizard crying dramatically. 🦎💦 It’s silly, but it sticks! Also, flashcards with example sentences help.

I use lachrymose from time to time. There's a kids book series with a place called Lake Lachrymose which introduced it into my vocabulary fairly early. The others, not really and I do love a big fancy word from time to time.

I've seen sacrosanct used a few times Of the rest, the only one I recognise is propinquity (which my phone autocorrected to promiscuity, lol) which I think I read in a Dickens book - Hard Times maybe?

My husband normally uses that kind of words, yes. But he’s in a minority of native users, I’m sure.

No. Although I was impressed that Bring Me the Horizon used sempiternal correctly.

I’m an English major and native speaker so I technically know the definitions of all of these words (except for perspicacious), but the only one of these words I’ve ever actually used is proprietary. Either way I’ve met plenty of native English speakers that wouldn’t know any of them.

An interesting tool for you to try out is Google's n-gram viewer. It will give you a feel for how common a word is. It can be tricky to tell when you look at an individual word, but if you include a more common word to compare against, it makes it easier. Here's an example: "keen" is a similar, but more common, word than "perspicacious." [Here's a comparison between the two.](https://books.google.com/ngrams/graph?content=keen%2Cperspicacious&year_start=1800&year_end=2022&corpus=en&smoothing=3) As you can see, "perspicacious" does appear in print, but not very often.

Propitiatory and proquintity are common in Edith Wharton stories. But most people only rarely talk like an Edith Wharton story. If ever.

All those words come from a latin root. To me they can be all easily understood, but only because I speak several Romance languages. And I've also studied latin for years. In Italian, for example, each one has a very similar translation (perspicacious -> perspicace, perspicuous -> perspicuo, propitiatory -> propiziatorio, and so on). Don't worry too much about remembering them, you will probably never use them..

I've heard perspicacious occasionally. In a video game I play one of the characters says it in a voice line (marvel rivals and Loki if anyone is interested)

I do not use them in daily life however I do know them. I may not be able to pronounce them correctly because most of them have been read rather than heard.

of those, sacrosanct is fairly common. perspicacious probably next. tbh mainly used by article writers who want to give the impression that they're cleverer than they are.

As a Native English speaker I can confirm I have never used any of those words.

Yes, but not necessarily in the forms you give. Like others have said, sacrosanct is not uncommon but I’ve never heard or read sacrosanctity. Perspicacious, yes; perspicuous, no. Propitiatory, yes. Lachrymose I’ve only encountered in older writings and propinquity is the word on your list I’ve seen the least often. Spellcheck in my phone didn’t even recognize it.

No, not hardly at all, I'm familiar with almost all of them (had to look up lachrymose), but I wouldn't use them in day to day conversation as most people wouldn't be familiar, and it could either make it sound like you're talking down to them, or like you're trying to show off, depending on the tone and circumstances.

Native speaker. Sacrosanct rarely, sancrosanctity never. Perspicacious even more rarely. The others very, very rarely. Lachrymose is more one for poetics and/or 18th/19th century writers; good to know, unlikely to use.

I've used "perspicacious" and "lachrymose" in both speech and online posts. The others I have used in my writings, but never in speech. They are rather rare, but you'll encounter them mostly in literature before 1900.

I know the first three fairly well. Perspicasious and perspicuous are related words that while I wouldn't expect to hear them every day, if I heard either one in daily conversation I wouldn't really be surprised. I use propitiatory semi-frequently, but specifically in a religious context. It's not an inherently religious word, but that's where it comes up for me, mostly. I had never heard of lachrymose, but I intuitively understood it, and after looking it up, my intuition was correct. My intuition stemmed from knowledge of the Latin word lacrimosa, which I only know because of Mozart's Requiem. If I had encountered it in a book or article, I would have looked it up to be sure I properly understood, unless the context made it clear my intuitive guess was correct. I've also never specifically heard the form sacrosanctity, but it's clearly the abstract noun form of sacrosanct. I looked it up for the purposes of this post because I wouldn't want to mislead anyone, but if I had encountered it in a book or article, I would not have looked it up. It's meaning is obvious.

In writing moreso than in common speech.

Native speaker: as someone else mentioned, these were SAT vocabulary words for me. I like to use such words from time to time, usually in written form, just to use them. And perhaps, admittedly, to show off, but only in a company that is likely to understand them. I do like to read the odd book that challenges my vocabulary. Not one where I need to pull up an online dictionary every other page, but... now and then. One of the great things about ebooks is with trivial effort you have a dictionary entry for a given word.

I have a robust vocabulary and I only know two of those words.

I have maybe used sacrosanct a couple times.

No, I've heard all of them and could define all except perspicacious (could now after looking it up). I'm a bit of a vocab nerd and am someone who has a tendency to use obscure words in normal speech, and perspicuous and sacrosanct are the only ones that I think I've ever used. So most people probably don't use any of them, I'd wager.

I’ve used sacrosanct, inauspicious & pedantic.

Only when I'm being fatuous.

BTW, it’s pronounced “EE-myoo.”

As a HS teacher I actively discourage overly Latinate vocabulary.

As a native speaker, I use most of these words, though not often. I might go several weeks or even months without saying any of them. It largely depends on whom I’m conversing with, as I usually adjust my diction to match. I tend to use “perspicuous” most frequently, followed by “lachrymose” and “sacrosanctity.”

I use “sacrosanct” sometimes, but I’m also autistic and well-read. None of those are common words. They’re good words, but not common.

This is a great question! I am a native English speaker (USA) and spent 3 years as a college writing tutor during my undergrad. In that job, I often suggested words to students that they had never heard of before. That being said, I have never heard of perspicacious or propinquity before. Feel free to ignore them for most purposes. The other four are more useful. Perspicuous is probably the most common and you should be familiar with its adv (perspicuously) and adj forms. Propitiatory is more common in its n (propitiation) and v (to propitiate) forms. Sacrosanctity is usually seen in its adv form (sacrosanct), and rarely in the noun form given here. I had to look up the meaning of lachrymose, but it’s a cool word! Have fun with it if you want to be dramatic. You might sound like a thesaurus if you do, though, and I can’t imagine using it outside of written text.

Some people must, because I've heard if most of them. I don't know what they mean, and I wouldn't expect most people to

I have never heard any of those words and I’ve lived in the US all my life. I don’t even know what any of them (except sacrosanctity) mean

Nope. I kinda know what they mean and could figure them out by context, but never use them. And I have multiple graduate degrees and write professionally.

Yes, I use them, but I am a nerd. You can find these words in academic texts and books with more florid language. I think the best way to acquire more of this type of vocabulary is to read classic literature!

I don't know what any of those words mean

Native speaker, I've NEVER seen or heard these words used. Except for sacrosanct. This seems to be a mental exercise used to prepare HS students for SAT tests. And valuable, for that reason.

I am a well-educated native speaker, and I have never heard any of the rare words you mentioned, although a related word "sacrosanct" will sometimes appear in discussions of politics, as in a certain party considered a certain policy to be sacrosanct. Overall, English has many more words than most other languages, but only a very small proportion of these words are in common use.

I’ve used perspicacious with some regularity. I know I’ve used lachrymose and propinquity, too.

I know them all but never use them, and see them highly infrequently. I would hazard a guess that most native speakers in the modern era would not recognize most of these words.

I think I've only ever seen those words in writing, and rarely.

Even native speakers use dictionaries. 

I would not commonly use any of these. I've heard of most (but not all), and I know the definition of a few. Some other forms might be more common - Like, you will hear "sacrosanct", as an adjective, way more than "sacrosanctity". It's not super common, but is not totally unusual to hear.

If someone uses these, it's usually either in an ironic, joking manner, or they are full of themselves trying to sound smart. There is usually a simpler or more common word to use in place of these. They aren't unknown, and most people will understand the word, it at least get the gist.

Some words are almost exclusively used in formal writing. I'm fairly well-read and I haven't heard of most of these, so they must be particularly rare. "Sacrosanctity" is the only one that I understand, although I've never seen it as a noun, only the adjective "sacrosanct". There's no shame in using a dictionary; native speakers do it all the time.

Several of these words in particular are used semi-frequently within theological contexts. Outside of those contexts, you are going to hear them used in conversational English.

I do use "sacrosanct" on occasion. Probably not more than a dozen times a year though... The rest of them? Not once. Though I have *seen* then, and know what they mean, I've never used them myself.

Some things are sacrosanct, but I don't think I've ever heard any of the other words in a genuine conversation.

I definitely use sacrosanct on occasion, but never sacrosanctity (I’m not sure that’s even a word). I’ve used lachrymose before, but usually only if I’m attempting to sound pretentious for comedic effect.

I know what they mean but those are not the kinds of words that are used in everyday conversation. They are typically found in literature or lectures. But not actual conversation.

No, the primary goal of language is communication. Using rare words is not communicating, it's just showing off. Now it's important to me to know them because I read a lot of literature. And when I do one of those "how big is your vocabulary size" tests, I usually score very high, but you wouldn't know that from speaking with me because I actually want people to understand me.

I've never even heard any of those words.

I'm not a native speaker, but this is what I can pick up: * Sacrosanct: very holy, very important * lachrymose: looks like it's derived from Latin lacrimare and I would guess tearful. I recognise the word from Dies Irae. * Propitiatory: I've heard of pituitary glands. No idea what they do or where they are. I can imagine this to be a medical term for something that lays in front of them. I could be wrong. * Perspicuous: like conspicuous, from Latin spicere, to look/to see. This could mean to be looking around, paying attention, being on guard. I would learn the roots and get a basic understanding of the source language, if you can.

Never

I've never heard anyone use those.

No.

I use words like this semi-frequently, but I'm a uni English instructor, author, and a certified word nerd.

Hmm. well let me see. * perspicacious - this has something to do with spontaneity, I think? good fortune or happy coincidence? * perspicuous - I don't recognize this one at all. conspicuous is a fairly common word, but I don't really know what "spicuous" means to understand what switching *con* "with" for *per* "around" would do to it. maybe...something easy to look over? assuming "spic" is related to the root of "spectacle", seems like a safe bet. * propitiatory - this sounds like it has something to do with a cliff to me. maybe because it sounds like "precipice" and "promontory"? So, I'd want to interpet this as either "deserving the caution of being near a cliff" or maybe "related to the potential energy of diving off a cliff" * lachrymose - "flooded with tears", I believe? I think the medical term for "tear glands" uses a similar root. * propinquity - this has some fascinating roots to it, but I'm not sure what they'd assemble to mean at all. "inquity" would be like, "infamous", I think? * sacrosanctity - ah, here's the rare word that I think I could use in a sentence but don't actually know the definition of. "sanctity" is "holiness", I believe, and "sacro" is "heart" or "chest" I think? I'd basically interpret that as "something held close to your heart", which seems roughly like how it is used. if pressed for a definition that fits how it's used, it would be "something beyond reproach". I think "lachrymose" and "sacrosanct" are the only two on here that I'd even come close to using. ah, checking the definitions, those are the only two I even got right haha. I think I was *vaguely* on the right track with "perspicuous" but didn't guess where it ended up. (lacrimal glands are the proper name for tear glands, so that worked though!) Well, despite how ineffective my approach was, I hope you can see that the way to learn words like these definitely isn't by using a flashcard with the word on one side and the definition on the other. You want to learn the *roots* of words, the history, and learn more words that are closely related at once. If you find a new word, find a word you know that's related to it in some way, and draw connections. *that's* how native speakers build vocabulary. edit: haha looking back I realize that I was closer to "perspicuous" than I thought, "something easy to look over" taken as "something easy to review" is actually exactly correct, it's just a shame that I really meant something more like "something easy to overlook" hahaha

Do you have any examples of “sancrosanctity” being used anywhere? I doubt that is a word anyone ever encounters to be honest.

I love 'lachrymose' I use it from time to time but have probably never spelled it correctly until now. The rest not really.

Maybe if I’m reading Faulkner but otherwise not really, no

I only use those words when I am talking down to someone.

The only one I’ve heard in the day-to-day is ‘lachrymose’. The others are more spelling bee/exam words that I haven’t come across since university. ‘Sacrosanctity’ is usually replaced by ‘sacrosanct nature’ for example. The others have completely fallen out of use as far as I’m aware.

None of them are common and I never previously encountered perspicuous. Actually, while the meaning of sacrosanctity is clear, I don't think I've seen it in that form either.

I am a 4th year history student minoring in English. I regularly deal with the language both in the modern context and more recently an 18th-19th Century context. I have never even heard any of these words. That being said, are you studying them for some sort of quiz or test? make a song or jingle out of em. Design an acronym. Make flash cards. If you’re just trying to expand your vocabulary: Read! Read alot. Do you already read alot? Good, now read more. You can never read enough. Read old literature. Read new literature. Read non-conventional literature. Read translated 15th century literature from China, if it floats your boat. Once you’ve read all you can of that, keep reading. thats the key.

Sacrosanct ... yes lachrymosa the song by evanescence

I use "perspicacious" as a puzzle having to do with spectacle, see through (perceive), and adjective when I'm teaching roots and prefixes. Somewhere, there is a nightclub named "propinquity." Or maybe it was ubiquity! lacheymose is like lagrimas "tears/crying" in Spanish Sacrosanct - I've eard t used in film and in prayer. sacred holy Let me find a root-word list for you so you can learn these and more.

I've literally never heard of the vast majority of those and I've been a native speaker for nearly 21 years

I need someone to whom I talk on call pls.… to learn and practice English

I use two or three of them on a regular basis, but not daily. I have high-level conversations about theology and philosophy. Most people do not have these types of conversations.

all ChatGPT: what is the average reading level in the U.S.. most people won’t use those words.

I don't think I've heard half of those words before, and I'm reasonably educated, so no.

I have used perspicacious before, but not daily. Sacrosanct, rather than sacrosanctity, as well.

American here 🇺🇸 Those words never come up in everyday conversation

Yes

I've heard of lachrymose, perspicacious, and sancrosanct, I would only use sacrosanct (in that form) and am not totally sure of the definition of perspicacious.

The only one of these that I use semi-regularly is propriety. I may have use sacrosanctity once or twice in my life but not regularly. The rest I have never used.

I have used about half of those words within the last 3 months (perspicacious, lachrymose , and propinquity, plus sacrosanct, not sacrosanctity.) Propitiatory it's been a few more months since I used.  I read plenty of books that use words like this, though, which is where I learned them. My family also read the same kind of books and we've had conversations using this type of vocabulary as long as I can remember. So like, hang out with other nerds who like words? We'll enjoy the words. Lol

I've never heard of any of these words

[Perspicacity](https://youtu.be/Vc0tMcabaA8?si=_2o9TQrg8EPiOCXq)

I know what they mean. I think I’ve only ever used sacrosanct.

This is kind of a function English. There are a limited set of common words we use constantly. There are a ton of hyper specific / precise words that are only used to describe the particular ideas they are associated with. Most English speakers would not use the particular words you pointed out. Even the people that would use them wouldn't use them often. But that's a normal function of English.

One way to get used to this level of discourse is to read writings by such enjoyable english authors as, say, Anthony Burgess. When I was at university I enjoyed finding rare gems of vocabulary in his novels.

Penultimate is my favorite. Means next to last...

I would use the adjective form 'sacrosanct' occasionally, but not 'sacrosanctity'. I'd probably just say 'sanctity' instead. I could see myself using 'lachrymose' if I was feeling a bit grand- but I'd be a lot more likely to use 'teary' or any number of more common words for 'miserable' instead. Of the rest, I've only ever heard of 'perspicacious' and I'm not even sure what it means.

Lachrymose maybe. I wouldn't use the others.

Those are what we call “SAT words.” We learn them for our college placement exams, then most folks forget them. For some of us they remain in the dusty attic of our minds. I will use sacrosanct (in that form) at least, as for the rest I know what they mean, but they don’t exactly fall off my tongue in conversation nor would I put them in prose.

I used "apoplectic" in casual conversation that, but that's one of my favorite words.

The word sacrosanct comes up in literature I read fairly regularly. My advice for remembering them is to learn the Latin root words.

I heard a judge say "pers.." well, not sure which of the perspic words it was lol I was a transcriptionist. Occasionally you get a verbose lawyer or judge sprinkling the judgment or argument with some of these bad boys. They don't flow well in normal speech, so they're only used when you have time to pace yourself (not conversation). That's me hearing the word. Don't recall reading any of those in everyday life, but I also don't read literature for fun.

I only know propitiatory because I have a theology degree

Lachrymose from Series of Unfortunate Events. I heard kids using it correctly in conversations for a bit after The Wide Window came out.

Where I grew up we would call these “Palabras Domingueras” - “Sunday Words”… used occasionally, possibly by a preacher. 😂😂😂 I recognize them, have used a couple of them; then again, I love languages and the way they often reflect a very different context of interpretation when talking about the same subject.

I use perspicacious, lachrymose, and **sacrosanct** as needed, but I'm weirdly verbose.

As someone with no literary background. Never.

Not commonly/everyday, except lachrymose and similar, at one time. I know the them and their meaning, but they are not words most people use in casual conversation. 

I've heard sacrosanct used a few times in a church context, and proprietary somewhat often, used when talking about electronics. The rest I only know from literature Edit: I didn't read closely enough and thought that "propitiatory" said proprietary. I've heard propitiatory quite often with regards to theology as well, as one of the Christian salvation theories of why Jesus' crucifixion is important is sometimes called the propitiatory atonement theory.

I know these words but wouldn't usually use them in daily conversation primarily because people would think I'm a knob. Which is sad, now that I think of it. I would note that, while "sacrosanctity" is rarely used, "sacrosanct" is fairly common.

My advice is just to associate them with synonyms, those are rare indeed

I do use them now and then, mostly in writing. I find that learning etymology really helps me with retaining vocab.

I'm confused why you would be forced to memorize random obscure words for an English major. I studied English in undergrad, and the focus was not on vocabulary memorization. English majors still have to look up words in dictionaries. Most of these words are very unfamiliar to everyday speakers, and they will make you sound like an elitist jerk if you use them, so I would honestly avoid effort to put them in your active vocabulary for everyday usage. They might have their usefulness for an author, but a few of them seem like specialized language to me (propitiatory, sacrosanctity). Perspicacious, lachrymose and sacrosanct are the ones that I can actively define, but I don't use them unless I want to sound ironic.

I’ve never used any of those

Focusing on vocabulary never kills. But what does kill? Neglecting Rythm. Focus on how your words sound. People aren’t swayed by what you say but rather — how you say it. You can always speak in a manner brimming with unnecessary sophistication. However, you always risk losing connection with the audience. Keep sentences short. Avoid redundant phrases. Make your writing punch.

I've been known to throw around perspicacious or sacrosanct (though not sacrosanctity) in everyday conversation. The other ones not so much, though I'm rather tempted to use lachrymose.

I would be comfortable using sacrosanct, perspicacious, and propinquity with my more erudite friends. Possibly lachrymose, if I was feeling especially loquacious.

Truthfully, I've seen the word "perspicacious" before, looked it up in a dictionary, and I still don't remember what it means.

I know them all; I occasionally use "perspicuous", "propitiate", and "sacrosanct" (the latter two being different forms from the ones you listed).

Native speaker, well-educated, I tend to use bigger words than I need when speaking. I don't think I've ever used any of the words you listed. I'm not sure what all of them mean either. They would come up so infrequently that for me I would just rely on a dictionary and would never put any brain power into memorizing them.

I use ‘perspicacious‘ and ‘perspicuous’ but not casually! These are all words derived from Latin and Greek. You will see them in literary texts from prior centuries, and also when a writer just feels like flexing some vocabulary. The best way to remember them, honestly, is to understand them by way of their roots in classical languages. Failing that, it’s brute force memorization. They’re fabulous words. You won‘t be using them much, yourself, but there’s no substitute for ‘propinquity’ when it‘s the word you need for any reason.

If I used those words (with the exception of sacrosanct), I would come off as pretentious. I know what they mean, just wouldn’t use them in everyday speech.

You’d see a few of those reading 19th century literature, but most of them wouldn’t be in common contemporary use.  Honestly, the best memory aid here would be the same I’d give to native English speakers … learn to recognize the  Latin root words.  One of the reasons they are “difficult” and “rare” is they’re a class of words that show off one’s learning, because knowing Latin was a sign of being educated. 

These words will simply not come up in conversation. You're good. Very rare words.

I’ve used all except “perspicuous” and “sacrosanctity”. (But I do use “perspicuity”, perspicacious” and “sacrosanct”. But in daily conversation? — Not very often at all.

I know what sacrosanctity means but I don't use it frequently. Propitiatory gets used at church. The others, I don't even know.

I knew all of those words before finishing secondary school, and some much earlier, but I learned most of them from reading tons of books, not from school. (I'm pretty sure I learned at least sacrosanct and lachrymose in school, the former I think from something in junior high and the latter from a poem in 9th- or 10th-grade Spanish class, as the Spanish word for "tears" is "lágrimas" -- I learned "defenestrate" there, too, as "fenestra" is a Spanish term for "window"). I *do* occasionally use them in conversation; I'm pretty sure I said "perspicacious" about something last week. While you might get less practice with them than with more-common words, you can memorize them like any other vocabulary term if they don't just stick with you. Learning components and cognates and related terms can help, too; for instance, you might not see "sacrosanct" much, but you'll encounter "sacrilege" and "sanctity" more often, and "lachrymose" makes more sense if you know that the lacrimal glands secrete tears.

I’ve heard/read them, but I think I’ve used all of one from this entire list.

All but “perspicuous” come up occasionally in mine. and @sacrosanctity” actually sounds like a humorous riff on the more common “sacrosanct.” Plain old “sanctity” usually suffices. Notice that several have religious uses, and much of my reading and writing deals with religion. So, eg, the difference between propitiatory and Eucharistic sacrifice is something that comes up a lot. Your mileage may vary. Also notice that these words all have Latin roots. Teachers sometimes put a lot of emphasis on fancy words derived from Latin, which I think is a mistake, but the best workaround is to study some basic Latin. Then you don’t have to memorize as much, because you can break the words down etymologically. In any case, words like this are fairly important in English writing from the 16th-19th centuries, when many writers knew Latin, and used it to coincide with new words on the spot, like Shakespeare’s “incarnadine” or half of Donne’s vocabulary.

Never

Lachrymose and sacrosanct are words i use, albeit rarely.

I’m a 24 year old college graduate from the US and I can confidently say I have literally never heard those words lol.

"Sacrosanct" is the only one I've heard be used with some measure of regularity. Every other word I have rarely ever seen used and wouldn't be able to tell you the meaning immediately.

Sure. But they are mostly formal written words. Perspicacious and sacrosanct are not especially uncommon. Now words like bumfodder, idiocracy, kleptocracy, might be more to the point. If you intend C2 level, they are all part of the language, taught and used in high school and college textbooks, in addition to obsolete forms needed to understand stuff written between 15 th and 20th century. Professionals have an entire chunk of words too.

I have heard of half those words purely because of a bit in the show Bojack Horseman where they were used as a way to emphasize someone's pretentiousness. Definitely not common in the slightest

Not sure if anyone has said this yet, but propitiatory/propitiation is a pretty common word in certain Christian circles. It's used to talk about how Jesus's sacrifice of his own life was how humans can now be reconciled to God ("the propitiatory work of Jesus" or phrases like this).

I recognize none of those.

I haven’t even seen half of those words before. 😅

Some of these I know by breaking down the Latin and Greek parts of the words.  Lachryma is a tear. The lacrymal duct produces tears. Lachrymose is a crying mood.  Perspicuous is like conspicuous but all the way through instead of just the surface. 

Yes, but only in highly specialized contexts or in quoting/analyzing pre-20th century works. "Perspecuity" is used in theology to refer to the idea, especially among Protestants, that God enables people to understand the Bible. Lachrymose is used in medical texts lachrymose ducts, where non-specialists would say tear ducts. I would say these words are generally archaic, and I would only focus on them to the extent that your studies are specialized in 19th or earlier century English. Edit: these are generally adjective forms which are based on somewhat more common nouns or verbs, such as perspecuous, sacrosanct, and propitiate.

My dad used to say, “How perspicacious of you!” dripping with sarcasm when as a child I would mansplain things to him!!!

I agree that most of these would mainly be found in older literature. And that "sacrosanct" still gets used (including in a metaphorical or joking way). But also, people might well say or write "propitiate" or "propitiatory" if they're talking about, say, animal sacrifice in ancient Greece or something.

Out of all of these proprietary is the only one used on a regular basis, so get to know that one

Perspicuous and perspicacious are probably the most common, followed by sacrosanct, and lachrymose. I would expect to come across them a few times a year, either in written or spoken English. I wasn't familiar with propinquity or the other one. ETA: I can't remember not knowing the word perspicuous, so I'm guessing I've known it since I was a child. I remember first learning perspicacious and lachrymose as a young adult. Any kid who has read *A Series of Unfortunate Events* will know lachrymose. To remember them, look up their etymology and take a genuine interest in it. Look up synonyms and other words with the same base/root/stem. Look at similarities, such as between perspicacious and perspex. Practice saying the words in sentences - even if you just say the sentences to yourself.

> sacrosanctity I've seen the adjective "sacrosanct" quite a lot, but I would have had to look up to see what the noun form was. > perspicacious I only know this word because Lisa Simpson says it in the episode where the teachers go on strike. And the joke is that she is var too verbose and wordy for an 8 year old because she uses words like this. The rest I may have seen at some point but I don't recognise them.

These are what used to be colloquially called 12 dollar words - fancy words that fancy people used. I use propitious now and then. Sacrosanct is word you’d use in an essay but almost never in regular conversation. I’ve read perspicacity and perspicacious in a book written in 1920, but haven’t seen it in modern literature, so to mind it’s not in general modern usage.

Sacrosanct/sacrosanctity, yes but rarely. Not the rest tho...

None of these are super common in daily usage, they’re rather obscure, some even archaic, but most if not all will be passively understood by the vast majority. As for what you can do to increase your chances of encountering rarer vocabulary in context? Read as far and wide as you can. Opt for higher register media - editorials, contemporary classics (1800s and onward) and don’t skimp on anything you don’t understand. Comprehension gaps are both data and blindspots for you to plug, rote memorization is largely agreed upon to be ineffective for long-term retention whereas learning words in context yields far better results for far longer.

Ok so I’ve never ever seen those words in my life 🫣

I’ve never even seen them before.

No.

No. Never. You might read them once in a blue moon. Anyone using these words would be regarded as pretentious.

I live in the UK and write for a living, so have a reasonably wide vocabulary. I have heard perspicacious (used rarely by my family, self-consciously), lachrymose (when someone is grasping for a synonym for tearful) and much more rarely propinquity. The others I have not heard at all. It's rare that anyone would be able to use these without being thought obtuse or pretentious.

Nobody uses words like those.

I think out of all these propitiatory and sacrosanctity are the ones I've heard most commonly, and propinquity I can't recall anyone ever saying. Kin/kinship/kindred are all words I'd reach for when wishing to express the meaning behind propinquity.

Sometimes I get "content" pushed at me on facebook which seems to think that because I'm not in an english speaking country I must be interested in lots of rubbish about how to learn english. And a lot of it IS rubbish. Some of it includes words like these - perhaps not these exact words - with captions like "upgrade your english" and suggest you can appear more competent in English by using "Loquacious" instead of "talkative" for example. Maybe some of these words might appear in Engish Exams but very few native speakers would use them in everyday conversation and even in formal writing they're not that common.

Are you Moira Rose?

I’ve encountered all of these, but usually in archaic and/or academic/literary texts. I would probably only use them in specific academic settings, or if I was being humorously over-the-top and pretentious about something. For most cases, those are spelling-bee study words, not everyday-use words. And I agree that “sacrosanctity” is weird. Plain “sanctity” works just as well, because it’s already rather stilted, archaic language, in a way that underscores its meaning. “Sacrosanctity” is… believable as a real word, barely, but it just sounds silly.

Yes! I love synonyms, especially when they rhyme. Id be happy to chat and talk about it more if you'd like!

Sacrosanct I'd use, the rest... nope. Native _level_ speaker.

These are all latin root words, what I was taught usually latin root words are very fancy words, it’s funny I prefer these words because they are easy to understand to me since I speak Spanish too. But not they are not commonly used they are more common on text book and speeches

No. Using those words in regular conversations would make you seem pretentious, ostentatious, and overly loquacious. I’m sure a lot of native speakers would find such sequipedalian vocabulary to be confusing.

I'm an English Literature nerd and English language teacher. I know the definitions of perspicacious, lachrymose, and sacrosanctity. I mixed up your word propitiatory for proprietory and those are not the same words at all. The other two, I wouldn't be able to define.  However, I semi regularly use perspicacity, which has the same root as perspicacious. There used to be a commercial jingle on TV for Cheez Whiz that went, "Cheez Whiz has personality! Personality! Has personaaality," I'll sub in "perspicacity" for personality, because I'm a word nerd and I like to sing sings to annoy my family. Your instincts are correct, I don't think anyone uses these words in daily life. You might see some in older, classical literature, but even well educated English native speakers would bristle at you using these words in speech. Ask me how I know.

Very rarely, but I've used perspicacious, lachrymose, and propinquity, and of course sacrosanct. The way to remember these sorts of words iseither (a) because they are interesting or (b) by their roots and parts to deduce their meanings.

Lachrymose is one of the 5 stages of intoxication: Jocose, verbose, bellicose, lachrymose, and comatose. Or, in plain words: Happy, talkative, angry, tearful and asleep.

As with much high-register language, its rarity of usage comes with the territory. The only effective way I've retained such vocabulary is through contextual usage. Write yourself a few sentences for each word and recite them and rewrite them. Keep these sentences in a word journal. Employ spaced repetition or the Leitner system to ensure retention. Best of luck! To answer your original question directly: no, these words aren’t common in everyday speech or writing. They’re mostly used in scholarly, analytical, or literary domains and typically found *in academic contexts* and in advanced writing (i.e., prestigious news sources, official scholastic tomes such as theses and dissertations, and technical or analytical writings such as historical or anthropological commentaries).

Interestingly, I am Italian living in an international bubble, and all those words sound fine to me as they come from latin 😂 i guess i would not use the specific examples but a few other fancy-sounding words that come from latin. A lot of formal, old fashion language has this source in English. This said those specific words are super rare, i have seldom seen them in writing or speaking. I wonder if as a linguist figuring out a bit about etymology could help you. Best of luck tho!

I know lachrymose from A Series of Unfortunate Events (book series), and sacrosanctity (the only somewhat common word on the list, in the form of sacrosanct). The others all have much more common and useful synonyms that I would use instead.

I don't. I think from that list, I've only heard the adjective "sacrosanct" before. (Never heard the abstract noun form of it "sacrosactity", but it makes sense.) And I think I've only heard it used semi-metaphorically in political debates, like to argue against continuing some tradition, or protecting some specific permission/right.

I'm a 50 year old native English speaker and I only know the meaning of one of those... And even that one, I have never used and likely never will!

I have used perspicacious in conversation, but usually with a humorous or sarcastic edge. I have heard sacrosanct plenty of times, and might have used it, but never sacrisanctity. Lachrymose is well known in written bits, but usually humorously, like describing a squonk. I have seen the others but very rarely.

People who know these words probably are people who have read a ton of English-language literature from various time periods (or people who purposefully set out to learn rare words). That's a small percentage of the population. In other words, most people don't know those words. If you are designing a test meant to identify such well-read people, it makes sense to include such rare words. The fact that they're rare doesn’t invalidate them.

Yay! I know all these words! Just teach English and literature for 20 years and you will too 😂 Seriously though, don't sweat it. Most native speakers don't know these words either, and their vocabulary doesn't suffer for it.  "Sacrosanctity" I've never actually heard, only sacrosanct. I'd call this a whole category of niche vocab: words that are already rarely used, and even then, usually only in one form. You might occasionally hear "sacrosanct" but no one and I mean no one ever says "sacrosanctity." I had a student yesterday doing vocab study pull up the word "enervate" and I had to point out that "enervating" is the more common usage (though in either case, it's a rare word to find in the wild.) Anyway, these words are like uncommon spices: you can go your whole life without ever using them, and no one will complain that your food is bland. But if you want to play with some new flavors, they can add notes and complexity to your dishes that you otherwise simply could not achieve.

Those words would be used in very nuanced and deliberate ways. You would also be speaking quite formally if you used them. I would imagine you are more likely to read them than hear them naturally being spoken, unless you were in an environment where they are used. Like sacrosanct is more common in religious dialogue. I think I last read ‘perspicacious’ in Pride and Prejudice.

You’re not going to find a lot of higher English used in day to day life as it’s not necessary. I’ll throw in a few words here and there that people don’t normally hear, and their expressions show they aren’t familiar with the word. Then I get to explain it lol.

As someone who learnt Latin and Greek at school, these words are easy to remember even without knowing them already. So that’s what I’d recommend.

No I am a native speaker from America and I don’t even know what any of those mean

Propitiate gets used in the study of classics, also apotropaic.

This might be a regional thing. Words like that are cumbersome not commonly used. They take too much time for obscure occurrences and situations. TL:DR no

Although I do not use the word lachrymose, I know its meaning; in medicine, the lacrimal gland is the tear duct, and in music, the instruction ‘lacrimosa’ means to play sorrowfully (eg, in Mozart’s Requiem). Perspicacious is another I know, but rarely use. As others have said, sacrosanctity is not often heard in that form. The other words I would probably figure out in sentence context — that happens a lot.

Sacrosanct is a great word to drop in a convo casually, but you may risk coming across as pompous, but in the right circumstance, it’s good.

Daily never. Conspicuous, is the only similar word I would expect to be somewhat common

I'm a linguist. I can guarantee no native speaker of any language is using every word in that language unless they are writing dictionaries or specializing in classic literature/translation. We will, however, make up works with impunity and there is a good chance 1) the interlocutor will understand it and 2) if they do, it's been 'made up' by several thousand other people.

These are very rare in daily life, but you will read them from time to time, especially in older books. Once you learn a critical mass of Greek and Latin roots and prefixes from other English words, it will become very easy to remember more.

Perspicacious: yes, occasionally. But only when talking with someone I know has a larger-than-average vocabulary. Sacrosanctity: I say "sacrosanct" from time to time. I've worked as a professional writer and have a larger-than-average vocabulary. I couldn't use those other words in a sentence and wouldn't understand what was meant from their use of I couldn't figure it out from context. But then, I didn't graduate with an English degree. You're literally studying the language, so I would be surprised if there wasn't an expectation that you had a larger command of the language than the average college student.

No. Sacrosanct might come up occasionally, but not the other ones.

Rarely but, yes. More common but still rare in more educated circles. Im used to hearing a lot of more rare words in more educated or 'sophisticated' circles. Rarely ill use sacrowhatever.

Authors love using the most obstus words they can find in their thesaurus and the critics rave over it. Normal humans do not use them.

I know all of these words, but I would only use them in written English not in everyday speech. Lachrymose is not used much because people would say tearful. Sacrosanct is the kind of word that might be used when discussing politics.

I can’t say I use them, but I do come across perspicacious and lachrymose regularly.

I don't know if these count as super rare, but I have said churlish in conversation, recently wrote tawdry, and heard someone say it behooves them, off the top of my head. I don't think that perspicacious is that rare. Sacrosanct is not uncommon. Some of the others in your list may be more unusual. It really depends on teh person.

I use them, but I do so to expand my base level intellectual cogitative freedom.