under-grown (adjective) immature: young, inexperienced
Sinonime: adolescent,
baby, babyish,
callow,
childish,
crude,
green*, half-grown,
imperfect, infantile, infantine,
jejune,
juvenile,
kid, kidstuff,
premature,
puerile,
raw,
sophomoric,
tender*, tenderfoot, underdeveloped, undergrown, undeveloped, unfinished, unfledged, unformed, unripe, unseasonable, unseasoned,
unsophisticated, untimely, wet behind ears,
youthfulAntonime: adult,
developed,
experienced,
grown,
mature,
old