Where does “sos” come from?

sos (Old French) comes from Latin subtus, from Latin sub, from Proto-Italic supo, from Proto-Indo-European upó, from Proto-Indo-European h₃ewp-.

Ancestry of “sos”, step by step

StepLanguageWordMeaning
1Latinsubtusbelow, underneath, beneath
2Latinsubunder, beneath; behind; at the feet of
3Proto-Italicsupounder
4Proto-Indo-Europeanupóunder, below
5Proto-Indo-Europeanh₃ewp-—

Words derived from “sos”

Every word from Proto-Indo-European h₃ewp- →Every word from Proto-Indo-European upó →Every word from Proto-Italic supo →