Swain is an English surname derived from the Old Norse personal name Sveinn (Sven, Sweyn), meaning a youth or young man. There are a number of variations in the spelling of the surname Swain, including Swaine, Swainne, and Swayne.

It is also common as a given name in history as Sweyn.

From this word meaning boy, young male or servant, are derived:

(1) The noun swain, meaning a rustic lover or boyfriend, cf. the numerous examples in Shakespeare's work, including his lyric, "[w]ho is Sylvia, what is she that all our Swains commend her" (from The Two Gentlemen of Verona).

(2) There are also specific nautical words involving swain: boatswain (literally "young man in charge of a boat") which can be seen in Shakespeare's The Tempest, and coxswain.