(noun, adjective)


1. characteristic of a lack of maturity

- immature behavior

Similar word(s): adolescent, jejune, juvenile, puerile, babyish, childish, infantile

2. (used of living things especially persons) in an early period of life or development or growth

Similar word(s): immature, new, adolescent, teen, teenage, teenaged, infantile, boyish, boylike, schoolboyish, childlike, childly, early, girlish, schoolgirlish, junior, little, small, newborn, preadolescent, preteen, puppyish, puppylike, tender, youngish, vernal, young, youthful, junior, young

3. not fully developed or mature; not ripe

Similar word(s): unaged, green, unripe, unripened

4. not yet mature

Similar word(s): adolescent, embryologic, embryonal, embryonic, inceptive, inchoative, larval, prepubertal, prepubescent, prepupal, pubescent, pupal, underdeveloped, premature, immature, young

5. (of birds) not yet having developed feathers

Similar word(s): unfeathered, unfledged

Sentences with immature as an adjective:

- You're only young once, but you can be immature the rest of your life.

- The man was immature for throwing a tantrum.


1. An immature member of a species.