[ in-fuh n-tl-iz-uh m, -tahy-liz-, in-fan-tl-iz-uh m ]
/ ˈɪn fən tlˌɪz əm, -taɪˌlɪz-, ɪnˈfæn tlˌɪz əm /


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.

Origin of infantilism

First recorded in 1890–95; infantile + -ism Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Examples from the Web for infantilism

  • The significance of "infantile sexual lesions" has also tended to give place to that of "infantilism of sexuality."

  • One of these suffered from infantilism, one turned out to be a drunkard, and the third became a social degenerate and drunkard.

    Being Well-Born|Michael F. Guyer
  • It is quite unnecessary to construct such dreams as a return to infantilism, as a regression, as the Freudians generally do.

    Psychoanalysis|Andr Tridon

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.