Where does “h₂ermos” come from?

h₂ermos (Proto-Indo-European) comes from Proto-Indo-European h₂er- — to fit, to fix, to put together.

Ancestry of “h₂ermos”, step by step

Step	Language	Word	Meaning
1	Proto-Indo-European	h₂er-	to fit, to fix, to put together

h₂ermos — Etymology, Origin & Word History | Etymology Explorer