adj. 1.  Not fully grown or developed: an immature plant. 2.  Marked by or suggesting a lack of normal maturity: silly, immature behavior. See Synonyms at  young. n.  An immature animal; a juvenile. [Latin immātūrus : in-, not; see  IN-1 + mātūrus, mature; see  mā-1 in the Appendix of Indo-European roots.] im′ma·turely adv. im′ma·turi·ty,  im′ma·tureness n.  | 
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved.







