The story
- Proto-Indo-European*h₂eydʰ-
- Proto-Hellenic*áitʰō
- Ancient Greekαἴθω (aíthō)
- Ancient Greekᾱ̓ήρ (āḗr)influ.?
- Ancient Greekαἰθήρ (aithḗr)
- Latinaethēr
- GermanÄther
- GermanEther
- Proto-Indo-European*swel-der.?
- Ancient Greekῡ̔́λη (hū́lē)
- GermanEthy
- Englishethyl
- Proto-Indo-European*médʰu
- Proto-Hellenic*métʰu
- Ancient Greekμέθυ (méthu)
- GermanMethy
- Englishmethyl
- Frenchpropionique
- Ancient Greekῡ̔́λη (hū́lē)
- Frenchpropyl-
- Englishpropyl
- New Latinammōnium
- Englishammonium
- Englishonium
- English todayemepronium
From e(thyl) + me(thyl) + pro(pyl) + -onium (“quaternary ammonium compound”).
Etymology from Wiktionary, CC BY-SA 4.0.