infantile

American

[in-fuhn-tahyl, -til] / ˈɪn fənˌtaɪl, -tɪl /

adjective

characteristic of or befitting an infant; babyish; childish.

infantile behavior.

Synonyms:

weak, immature, puerile

Antonyms:

mature, adult
of or relating to infants or infancy.

infantile diseases.
Physical Geography. youthful.

infantile British

/ ˈɪnfənˌtaɪl, ˌɪnfənˈtɪlɪtɪ /

adjective

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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

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

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

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

“It was offensive and infantile, especially as the moms were all trying to figure out childcare during summer break.”

From Salon • Jul. 31, 2024

The mascot of the band, known as “Booji Boy,” was an infantile urchin in a rubber mask.

From Los Angeles Times • Jan. 21, 2024

“Sitting next to you. Your mother. Who held your hand as you took your first infantile steps.”

From "The Fault in Our Stars" by John Green

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023