Where does “sennor” come from?

sennor (Old Spanish) comes from Vulgar Latin senjor, from Latin senior, from Latin senex, from Proto-Indo-European sénos — old.

sennor (Old Spanish): lord

Definitions

Step	Language	Word	Meaning
1	Vulgar Latin	senjor	master, elder, lord, nobleman
2	Latin	senior	older, elder; rather old; a lord, sir; an abbot
3	Latin	senex	old, aged, elderly; old person, old man, old...
4	Proto-Indo-European	sénos	old

sennor — Etymology, Origin & Word History | Etymology Explorer