The English word cowboy has an origin from several earlier terms that referred to both age and to cattle or cattle-tending work. The English word cowboy was derived from vaquero, a Spanish word for an individual who managed cattle while mounted on horseback. Vaquero was derived from vaca, meaning "cow", which came from the Latin word vacca.

Our term cowboy was first documented in the English language by 1725. A direct translation of the Spanish word vaquero, one who manages cattle from horseback, cowboy has come to mean the same thing — a man employed to take care of grazing cattle on a ranch (OED).

cowboy (n.) 1725, "boy who tends to cows and drives them to and from pasture," from cow (n.) + boy. American-English sense of "man employed to have care of grazing cattle on the Great Plains for a stockman or ranch, doing his work on horseback" is by 1849.