[ in-fuhn-tl-iz-uhm, -tahy-liz-, in-fan-tl-iz-uhm ]
/ ˈɪn fən tlˌɪz əm, -taɪˌlɪz-, ɪnˈfæn tlˌɪz əm /
Save This Word!


the persistence in an adult of markedly childish anatomical, physiological, or psychological characteristics.
an infantile act, trait, etc., especially in an adult.
a speech disorder characterized by speech and voice patterns that are typical of very young children.



Were you ready for a quiz on this topic? Well, here it is! See how well you can differentiate between the uses of "was" vs. "were" in this quiz.
Question 1 of 7
“Was” is used for the indicative past tense of “to be,” and “were” is only used for the subjunctive past tense.

Meet Grammar Coach

Write or paste your essay, email, or story into Grammar Coach and get grammar helpImprove Your Writing

Meet Grammar Coach

Improve Your Writing
Write or paste your essay, email, or story into Grammar Coach and get grammar help

Origin of infantilism

First recorded in 1890–95; infantile + -ism
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

Example sentences from the Web for infantilism

British Dictionary definitions for infantilism

/ (ɪnˈfæntɪˌlɪzəm) /


  1. a condition in which an older child or adult is mentally or physically undeveloped
  2. isolated instances of infantile behaviour in mature persons
childish speech; baby talk
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

Medical definitions for infantilism

[ ĭnfən-tl-ĭz′əm, ĭn-făntl- ]


A state of arrested development in an adult, characterized by retention of infantile mentality, accompanied by stunted growth and sexual immaturity, and often by dwarfism.
Extreme immaturity, as in behavior or character.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.