Where does “Caballero” come from?

Caballero comes from Spanish caballero, derived from Late Latin caballarius, from Latin caballus, ultimately from Gaulish caballos.

Ancestry of “Caballero”, step by step

Step	Language	Word	Meaning
1	Spanish	caballero	gentleman; cowboy; horseman
2	Latin	caballārius	—
3	Latin	caballus	horse; nag; pack-horse, jade, hack
4	Proto-Celtic	kaballos	horse

Caballero — Etymology, Origin & Word History | Etymology Explorer