adolescent

1 being in the early stage of life, growth, or development an adolescent sheepdog, who hasn't quite gotten the hang of keeping the sheep huddled together Synonyms young, immature, juvenile, youngish, youthfulRelated Words ephebic, minor, preteen, subadult, teenage (or teenaged), underage; embryonic, emergent; callow, green, inexperienced, puerile, raw; babyish, childish, childlike, infantile, infantine, kiddish; undeveloped, unfinished, unfledged, unformed, unripe, unripened; blooming, blossoming, burgeoning, flourishing, floweringNear Antonyms aged, aging (or ageing), ancient, elderly, geriatric, long-lived, old, older, oldish, senescent, senior; full-blown, full-fledged; golden, mellow, ripe, ripened; middle-aged; anile, decrepit, doddering, over-the-hill, senile, spavined, totteryAntonyms adult, grown-up, mature, matured

2 having or showing the annoying qualities (as silliness) associated with children would hope that the college students had outgrown such adolescent behavior Synonyms childish, babyish, immature, infantile, jejune, juvenile, kiddish, puerileRelated Words boyish, brattish, bratty, girlie (or girly), girlish; childlike, innocent, naive (or naïve), simple, simplistic, unsophisticatedNear Antonyms unchildlike; cosmopolitan, experienced, knowing, smart, sophisticated, worldly, worldly-wiseAntonyms adult, grown-up, mature

3 lacking in adult experience or maturity took a group of adolescent recruits and turned them into professional warriors Synonyms callow, green, immature, inexperienced, juvenile, puerile, raw, unfledged, unformed, unripe, unripenedRelated Words babyish, childish, infantile, infantilized, infantine; boyish, girlish, juvenescent, kiddish, young, youngish, youthful; maidenly, virginal; ingenuous, innocent, naive (or naïve), tender; unknowing, unseasoned, unsophisticated, untrained, untriedNear Antonyms advanced, precocious; knowing, savvy, sophisticated, worldly, worldly-wiseAntonyms adult, experienced, grown-up, mature, ripe