Why zodiac sign “cancer” uses same word as disease?

The zodiac sign wasn't named for the disease, the disease was named for a tumor that resembled a crab and the zodiac sign was also named for the crab. They didn't decide to associate a zodiac sign with the disease.

We don't say bull, virgin or scales, in the context of astrology cancer has nothing to do with the disease.

Cancer, the crab comes from the same Greek root word Karkinos. Turmors with swollen veins running from them looked like crabs limbs to physicians back in the day

Cancer the disease was named after crabs because Hippocrates noticed that cancerous tumors often has protrusions that looked like the legs of a crab, so he called cancer "crab-like" Krakinos is the Greek word for crab, which became the Latin word cancer. The disease kept the Latin name while English developed its own name for the animal

The constellation and the tumor were both independently named after crabs

What do you mean you "know that the word cancer is only used for the disease"? You write a whole chapter but don't want to punch "cancer" into a dictionary? #letmegoogleitforyou

The word cancer (disease) actually comes from the same etymological root as cancer (zoodiac), meaning lobster

In English we call all Zodiac signs by their Latin names. E.g. "Aries" instead of "ram" or "Gemini" instead of "twins."

Zodiac sign came before the word Cancer was used for the disease

Ohh, this is such a good question! I never thought about it before, but now that you mention it, it is kinda weird 😅 In English, "Cancer" (the zodiac) comes from Latin, where it literally means "crab." But yeah, the disease got the same name because old doctors thought tumors looked like crabs?? (Super strange, I know.)

Cancer from the Latin for crab. The constellation represents a crab. The disease was so-named because of the crab-like shape of tumors. So the disease actually uses the same name as the zodiac sign. Not the other way around.

Interestingly enough, it is cancer in Brazilian Portuguese but caranguejo (crab) in European Portuguese.

Etymology entry on the word cancer: late Middle English: via Anglo-Norman French from Latin, ‘crab’, also denoting various diseases, related to Greek karkinos in the same senses, said to have been applied to such tumors because the swollen veins around them resembled the limbs of a crab. 

Cancer means crab and back in the day they thought tumors resembled crab claws

'cancer' means crab in Latin. the zodiac signs all have Latin names.

Because it uses the name of an actual crab from Greek mythology, and that crab's name was Cancer. Hera sent it to distract Hercules during his fight with the hydra. After it was killed, Hera placed him among the stars to honor him. The name of the Zodiac is not related to the disease.

In other languages the disease and the animal are called the same. Though in Polish it means crayfish

They are all crabs. The disease is called "cancer" because ancient Greek physicians compared the way that cancerous tumors spread to the claws of a crab. Nowadays, the term is more general and includes diseases that don't have naked-eye visible tumors, and tumors which spread in different ways, but the first cancers that were recognized in antiquity reminded doctors of crabs, so the name stuck. The star formation looks kind of like a crab, and the disease looks kind of like a crab, and a crayfish is related to a crab, so they are all called "crab."

“Cancer” comes from Latin for crab that’s why its used for the zodiac. The disease was named that way because tumors looked like crab legs spreading

Probably something to do with latin

Some astrologists use the term “Moon Child” to refer to those born under the sign, but seems like if we’re breaking the Latin name rule, we could call the constellation “Crab” and people born under that sign “Crabs”, or even “Crabby Cakes”. “Hi, I’m a Gemini” “I'm a Virgo” “I'm a Crabby Cake”.

My Zodiac sign is cancer and I've had cancer. I also don't like that it's called that.

They both come from the Latin word for crab. The Romans thought that tumors looked like crabs.

Crabs is also a disease

Quick correction of your post: Why does the zodiac sign ‘Cancer’ share a name with the disease? Why isn’t it called crayfish or crab? It’s strange that the zodiac is being associated with this horrible disease.  In my langauge, we just call it crayfish. Ive always associated it with crayfish because it’s a lot more logical and better related  to the sea animal.  I know that in English cancer is used both for the sign and the condition and, that crayfish is another word completely. It’s just so strange to me

cancer means 'crab' in Latin. it's as easy as that but to be honest I was also confused at first

How are they different in your native language? Because in mine both disease and constellation also share a word.

We don’t use regular English words for zodiac signs. Otherwise they would be fish, bull, twins, lion, virgin, etc.

Others have pointed out the long historical connection between crabs (the creature) and cancer (the diseases) and tha the word "cancer" also meant 'crab' at one point. I will add that in Hungarian it is the same. The work "rák" means the both the disease and crab or lobster. I strongly suspect that this is true in other languages as well.

Yeah cancerians are known to be one of the sweatiest people in the world of all 12 zodiacs and the name is the only downfall with this sign… I want to know the same as to why it couldn’t have been named something different and less ominous