I would like to point out that this meaning is not likely to occur in everyday speech, it's κάβουρας in modern Greek. It's the same as saying cancer in English. Who is going to take that as "crab"? In zoology καρκίνος is used for crab, the same way English does:https://en.wikipedia.org/wiki/Cancer_(genus)
Thank you for the insight. It happens the same way in Spanish as in English and Greek, then. The missinterpretation occurred because I used a German to Greek dictionary carelessly. At least in German, the crab is commonly called "der Krebs", the word used for cancer. It is even marked sometimes as the first meaning: http://www.duden.de/rechtschreibung/Krebs
The first meaning in this next page, however, suggests that it is not the same as comparing it to cancer in English: http://www.greek-language.gr/greekLang/modern_greek/tools/lexica/triantafyllides/search.html?lq=%22%CE%BA%CE%B1%CF%81%CE%BA%CE%AF%CE%BD%CE%BF%CF%82+2%22&dq=
And of course the genus is the same in every language, since genus and species are always given in Latin in taxonomy.
Yes, but in Greek zoology (when) we don't use the Latin one, we use the Greek "καρκίνος". That's why it says" καρκίνος 2 ο : I1. (ζωολ.) κάβουρας." (ζωολ.) is zoology. Otherwise it would say καρκίνος without the (ζωολ.) part, if it was an everyday word. ;) The crab=κάβουρας belongs in καρκινοειδή=Crustacea in Latin, for example.