infantile
Americanadjective
-
like a child in action or behaviour; childishly immature; puerile
-
of, relating to, or characteristic of infants or infancy
-
in an early stage of development
Related Words
See childish.
Other Word Forms
- infantility noun
Etymology
Origin of infantile
From the Latin word infantīlis, dating back to 1690–1700. See infant, -ile
Explanation
Infantile means immature or childish. Thumb-sucking and temper tantrums are examples of infantile behavior. Doctors use the word infantile just like you'd expect: to describe things having to do with infants or babies. The rest of us, though, generally use this adjective when someone's being a brat or a crybaby or otherwise behaving immaturely. If someone refers to your sense of humor or your style of argument as "infantile" they are not offering you a compliment. They might be trying to tell you to "grow up."
Vocabulary lists containing infantile
Out of the Dust
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Made You Look: Synonyms for "Immature"
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Bronx Masquerade
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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.
And don’t get me started on the endless, infantile standing ovations.
From MarketWatch • Feb. 24, 2026
“Colin is deeply romantic and has a sort of slightly infantile version of romance,” Lighton said of the character the story unfolds through.
From The Wall Street Journal • Feb. 10, 2026
Emojis can have an "infantile connotation" which could lead to people perceiving you as younger, less senior, capable or responsible, he says.
From BBC • Dec. 14, 2025
“There was a lo-fi quality about it. It had something candid that didn’t necessarily have an infantile tone but had a lightness. And we could add lyrics to that music.”
From Los Angeles Times • Nov. 21, 2025
“Phineas,” Brinker said with dignity, “please don’t give us your infantile lecture on world affairs at this time.”
From "A Separate Peace" by John Knowles
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.
