- not mature, ripe, developed, perfected, etc.
- emotionally undeveloped; juvenile; childish.
- Physical Geography. youthful(def 5).
- Archaic. premature.
- not fully grown or developed
- deficient in maturity; lacking wisdom, insight, emotional stability, etc
- geography a less common term for youthful (def. 4)
1540s, “untimely, premature,” from Latin immaturus “untimely, unripe,” from assimilated form of in- “not, opposite of” (see in- (1)) + maturus (see mature (v.)). In 16c., usually in reference to early death; modern sense of “not fully developed” first recorded 1640s. In reference to mentalities or behaviors not considered age-appropriate, from 1920.
- Not fully grown or developed.