Where does “sou” come from?

sou (Old Portuguese) comes from Latin suus, from Proto-Italic sowos, from Proto-Indo-European sewos, from Proto-Indo-European swé — self.

Ancestry of “sou”, step by step

StepLanguageWordMeaning
1Latinsuushis, her, its, their
2Proto-Italicsowoshis, her, its, their
3Proto-Indo-Europeansewos(one's) own; his, her, its
4Proto-Indo-Europeanswéself
Every word from Proto-Indo-European swé →Every word from Proto-Indo-European sewos →Every word from Proto-Italic sowos →