The word squirrel is probably most interesting because of the sheer heterography in its past. In Middle English, it altered between squyrelle and squirel, and before that, it was spelled esquirel in Anglo-Norman, from French escurel. Note how both the q and the double rs were dropped by here. In Latin, it underwent variations such as scuriolus and scurius, and through sciurus, it ultimately derives from the Ancient Greek term skiourous, which still meant "squirrel" figuratively, but literally meant "shadow-tailed". This is because it is a portmanteau of two words: skia, meaning "shadow", and oura, meaning "tail". The former is from Proto-Indo-European skeh, also meaning "shadow", and the latter is from Proto-Indo-European ors, meaning "backside" or "buttock", even. Not too much semantic change in that word, but it's notable nonetheless; all words matter!
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.