helicopter and competition come from the same PIE root peth₂- "to fly"

Etymology Trees of competition & helicopter

Based on Wiktionary data, the PIE root peth₂- originally meant "to spread out" and "to fly" (as in spreading one's wings). From there, the word developed in two interesting directions through different semantic shifts.

helicopter:

PIE peth₂- "to spread out, to fly"
PIE péth₂r̥ "wing, feather"
Ancient Greek pterón "wing, feather, wing-like object, winged creature"
French hélicoptère (hélix \+ pterón), coined in 1861 by the inventor Gustave de Ponton d'Amécourt

competition:

PIE peth₂- "to spread out, to fly"
PIE péth₂eti "to fly"
Latin petere "to head for, to aim at, to seek" (probably from "to fly towards")
Latin competere, literally "to seek together"
Late Latin competitio "rivalry" (seeking the same thing as someone else)
French compétition

The tree and the sources used to build it are available here if you want to go deeper.

I made the graph using Miraris (which is a free site I built). You can actually make your own graphs here if you know any related words, or even discover relationships on the fly by searching for a word and exploring its root's descendants (which is pretty fun I think). I'd love your feedback if you have any!

Anyway, do you know any surprising or interesting pairs of related words?

I created a list of the ones I like, and I'll keep adding to it as people share their own suggestions in the replies.

https://redd.it/1wybgwq
@r_etymology