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.
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
The two did a nice job portraying teenagers who go back and forth from sincere to ridiculously immature, but the best part was their horror when Jost fired back.
From Los Angeles Times • Apr. 12, 2026
Sticky buns feel immature once you have said korvapuusti.
From Salon • Mar. 8, 2026
Infection during pregnancy poses additional risks, as it can cause severe health problems for developing babies with immature immune systems.
From Science Daily • Jan. 27, 2026
And then I had to confess to Julia how stupid and immature I had been on those days leading up to my birthday.
From "100 Sideways Miles" by Andrew Smith
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.
