Where does “Senio” come from?

Senio (Italian) comes from Latin senium, from Latin senex, from Proto-Indo-European sénos — old.

Ancestry of “Senio”, step by step

Step	Language	Word	Meaning
1	Latin	senium	feebleness of age, decline, debility; old man;...
2	Latin	senex	old, aged, elderly; old person, old man, old...
3	Proto-Indo-European	sénos	old

Senio — Etymology, Origin & Word History | Etymology Explorer