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caballero m. (Noun, Adjective) "gentleman," "cowboy," "knight;" "gentlemanly"

11th cent. From Late Latin caballarius "horseman," from Latin caballus "horse" (whence caballo) and -arius, an agent-forming suffix (see -ero).

Also the origin of the surnames Caballero, Caballeros.

Romance: Western Vulgar Latin: Asturian caballeru, Portuguese cavaleiro, Galician cabaleiro, Catalan cavaller, French chevalier, Italian cavaliere; Eastern Vulgar Latin: Romanian cavaler; Sardinian cabaglieri