Definition of boy :
1. A male child, from birth to the age of puberty; a lad; hence, a son.
2. In various countries, a male servant, laborer, or slave of a native or inferior race; also, any man of such a race.
3. To act as a boy; - in allusion to the former practice of boys acting women's parts on the stage.
child prodigy, bastard, nipper, that's the way, shaveling, nephew, cherub, sport, bull, adolescent, puppy, buster, mother's boy, bevy, mate, gaggle, well done, blue, youth, kids, all-American, cock, schoolboy, buddy, sonny, bunch, macho man, boy wonder, gang, tad, young man, conference, daughter, bravo, shaver, boomerang kid, junior, alpha male, connect, backfield, cockerel, small fry, beings, little guy, swain, old man, boyo, lot, clan, male child, cadet, bairn, issue, bro, center, good thinking, dog, good boy/girl, dude, bud, imp, boar, whippersnapper, crew, bullock, let's hear it for, you're a genius, rogues' gallery, center forward, son, niece, master, little gentleman, (nuff) props to someone, beau, callant, club, firstborn, mob, back, ballplayer, billy goat, family man, laddie, posse, boychick, compliments to someone
man (part of speech: noun)
youngster (part of speech: noun)