- boy mid-13c., boie "servant, commoner, knave, boy," possibly from O.Fr. embuie "one fettered," from V.L. *imboiare, from L. boia "leg iron, yoke, leather collar," from Gk. boeiai dorai "ox hides." But it also appears to be identical with E.Fris. boi "young gentleman," and perhaps with Du. boef "knave," from M.Du. boeve, perhaps from M.L.G. buobe. This suggests a gradational relationship to BABE (Cf. babe). For a different conjecture:In Old English, only the proper name Boia has been recorded. ME boi meant 'churl, servant' and (rarely) 'devil.' In texts, the meaning 'male child' does not antedate 1400. ModE boy looks like a semantic blend of an onomatopoeic word for an evil spirit (*boi) and a baby word for 'brother' (*bo). [Liberman]Used slightingly of young men in M.E.; meaning "male negro slave or Asian personal servant of any age" attested from c.1600. (Words for "boy" double as "servant, attendant" across the I.E. map -- e.g. It. ragazzo, Fr. garçon, M.E. knave, O.C.S. otroku -- and often it is difficult to say which meaning came first.) Exclamation oh, boy attested from 1892.
Etymology dictionary. 2014.