Bill:
You said:
There is a bone in the human skull, the lower part of the nasal septum, called the "vomer" which seems to be ultimately from the same root as vomit. It was also a Late Latin word for ploughshare. I can't quite figure out why.
Well, there isn't any connection, which is probably why you cannot figure it out.
Vomer is a noun, deriving directly from the latin word vomer, a ploughshare.
Vomit as a verb derives from vomo, vomere, vomiti, vomitus, to Bushusuru.
It's just cooincidence, I believe, that they start with the same first three letters. But there are a LOT of words like that, doncha know?
TTF