caballería
/kabaʝeˈɾia/ · B2 · noun · f
cavalry
🐎⚔️ caballo (horse) + -ería (group) = a group of horse riders
Caballería comes from caballo, meaning horse, plus the suffix -ería, which names a group or collection. So it is the horse-borne troops. It also extends to any animal you ride, a mount. The root is Latin caballus, a workhorse.