Where does “summersus” come from?

summersus (Latin) comes from Latin summergō, from Latin sub, from Proto-Italic supo, from Proto-Indo-European upó, from Proto-Indo-European h₃ewp-.

summersus (Latin): sunken, submerged, underwater; drowned;...

Definitions

Step	Language	Word	Meaning
1	Latin	summergō	to sink, submerge, submerse
2	Latin	sub	under, beneath; behind; at the feet of
3	Proto-Italic	supo	under
4	Proto-Indo-European	upó	under, below
5	Proto-Indo-European	h₃ewp-	—