adjective
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not fully grown or developed
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deficient in maturity; lacking wisdom, insight, emotional stability, etc
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geography a less common term for youthful
Other Word Forms
- immaturely adverb
- immatureness noun
- immaturity noun
Etymology
Origin of immature
First recorded in 1540–50, immature is from the Latin word immātūrus unripe, hence, untimely. See im- 2, mature
Explanation
Use the adjective immature to describe something that is not fully grown: “Elizabeth rescued an immature sparrow that had fallen from its nest during the storm.” When used in a general sense, immature describes something in an early stage of development, such as an immature fruit tree or an immature political system. When applied to people, however, immature is often used to describe someone who behaves in a childish way. So if your 42-year-old brother spends the entire holiday weekend playing video games and then throws a temper tantrum when you ask him to help with the dishes, the word you’re looking for to describe him is probably immature.
Vocabulary lists containing immature
List 5
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Brown Girl Dreaming
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Made You Look: Synonyms for "Immature"
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Parvovirus, also known as slapped cheek syndrome, is usually harmless to children but Arthur was extremely unwell because of his immature immune system.
From BBC • Apr. 21, 2026
The executive, Benjamin Baker, testified that the messages were “very immature and unacceptable.”
From Los Angeles Times • Apr. 15, 2026
"At the time, the prevailing consensus was that the Nanotyrannus holotype skull represented an immature Tyrannosaurus rex, and was not a separate species," said Griffin, assistant professor of geosciences at Princeton.
From Science Daily • Apr. 15, 2026
The Army itself advises soldiers to “maintain the high ground,” and research shows that rapid-fire calls made under pressure by the morally immature lead to disaster.
From Slate • Apr. 13, 2026
It seemed kind of silly and immature, but there wasn’t anything I could do about it.
From "The Million Dollar Shot" by Dan Gutman
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
