The word cervical, if you bothered to notice, refers to two different parts of the human body. It may mean "the lower part of the uterus", as in cervical cancer, or "relating to the neck", as in cervical vertebrae. Cervix is the same story, though normally more exclusive to the uterus. How did this come about? To find out, we look at the farthest root, the Proto-Indo-European word kerh, which... wait for it... meant "head". This hodgepodge of body parts is really weird until you realize that the neck is attached to the head, and is a logical derivation as the word traveled into Latin as cervix, or "neck". This passed into English for scientific use in describing the neck, but doctors began overusing the word and applying it for anything that remotely looked like a neck. This is why by the eighteenth century cervix also began to be applied to the "neck of the womb"; same story with its derivative, cervical. "The part of the uterus" is a more common definition now because it's used much more; people get afflictions down there more often than in the neck. However, it also stands to etymological logic that any malignant tumor above the shoulders can also be considered "cervical cancer".
Hello! I'm Adam Aleksic, a sophomore studying government and linguistics at Harvard University, where I co-founded the Harvard Undergraduate Linguistics Society. In addition to etymology, I also really enjoy politics, vexillology, geography, board games, conlanging, and law.