My favourite etymology fact is that “helicopter” is helico-pter — Greek for “spiral wing”. It’s obvious when pointed out, but I’d never have realized it on my own since in English it’s always broken down as heli-copter!

Relatedly, Magic: The Gathering has a creature type called Thopter, which is a rebracketed abbreviation of the word “ornithopter” (from ornitho- meaning bird, and pter meaning wing).