The story
- Proto-Indo-European*gʷʰer-
- Proto-Indo-European*gʷʰermos
- Proto-Hellenic*kʷʰermós
- Ancient Greekθερμός (thermós)
- Englishthermo-
- Englishreversible
- English todaythermoreversible
From thermo- + reversible.
Etymology from Wiktionary, CC BY-SA 4.0.