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.
The breakthrough arrived in 1955 when Dr. Jonas Salk introduced a safe and effective injected vaccine, funded by grassroots donations to the March of Dimes, then officially known as the National Foundation for Infantile Paralysis.
From The Wall Street Journal • Apr. 24, 2026
Americans responded by sending their dimes to the National Foundation for Infantile Paralysis, otherwise known as the March of Dimes.
From National Geographic • Jan. 2, 2024
Infantile cystinosis, the most common and most severe type of cystinosis, occurs as the result of an accumulation in the body's cells of cystine, an amino acid.
From Science Daily • Dec. 11, 2023
Salk's work "was supported by the National Foundation for Infantile Paralysis, better known as the March of Dimes," Jacobs told Salon by email.
From Salon • Nov. 1, 2023
Infantile Cerebral Palsy sometimes brings about a condition known as "Spastic Speech," while whooping cough, scarlet fever, measles, meningitis, infantile paralysis, scrofula and rickets are sometimes responsible for the disorder.
From Stammering, Its Cause and Cure by Bogue, Benjamin Nathaniel
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.
