teenager

preteen, preteen-ager, subteen, teen, teener, teenybopper, tween

bairn [chiefly Scottish], bambino, bud, chap [Southern & Midland], chick, child, cub, juvenile, kid, kiddie (also kiddy), kiddo, moppet, sprat, sprout, squirt, whelp, youngling, youngster, youth

adolescent, minor

kindergartner (also kindergartener), preschooler, rug rat [slang], schoolboy, schoolchild, schoolgirl, schoolkid

babe, baby, bantling, infant, neonate, nestling, newborn, toddler, tot, tyke (also tike), weanling

brat, imp, jackanapes, mischief, monkey, rapscallion, rascal, rogue, urchin, whippersnapper

cherub

lad, nipper, shaver, stripling, tad

bobby-soxer, hoyden, tomboy