Harsh, but fair ?
@craigb - I've delved quite deeply (as you might imagine) into etymology as it really interests me. For my sins, I had to study Latin at school and although I loathed it at the time, it certainly helps in getting a handle on the roots from which a lot of modern words derive.
As per your examples, a lot of things happen to share the same words, but the derivation/source of that particular word may be completely different.
Edit - spelling [now there's irony ?]