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
Synonym Usage
See childish.
Other Word Forms
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.
Bloom was apt to address or sign his letters to Hollander using infantile variations of “Foofy mein Foofy”: “Thy Foo,” “Foofy,” etc.
From The Wall Street Journal • May 29, 2026
And don’t get me started on the endless, infantile standing ovations.
From MarketWatch • Feb. 24, 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
NASA’s James Webb Space Telescope’s high resolution, near-infrared look at Herbig-Haro 211 reveals exquisite detail of the outflow of a young star, an infantile analogue of our Sun.
From Salon • Oct. 8, 2024
“If ever I hear again of any lapse from a proper standard of infantile decorum, I shall ask for your transference to a Sub-Centre— preferably to Iceland. Good morning.”
From "Brave New World" by Aldous Huxley
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.
