infantile

UK: /ˈɪnfəntaɪl/

US: /ˈɪnfənˌtaɪl, -tɪl/

US: (in′fən tīl′, -til)

WordReference Random House Learner's Dictionary of American English © 2025

in•fan•tile /ˈɪnfənˌtaɪl, -tɪl/   adj. 

1. characteristic of or behaving like an infant:
   infantile temper tantrums.
2. of or relating to infants or infancy:
   infantile sicknesses.

WordReference Random House Unabridged Dictionary of American English © 2025

in•fan•tile  (in′fən tīl′, -til), adj. 

1. characteristic of or befitting an infant; babyish;
   childish:
   infantile behavior.
2. of or pertaining to infants or infancy:
   infantile diseases.
3. [Physical Geog.] youthful (def. 5).

• Latin infantīlis. See infant, -ile
• 1690–1700

in•fan•til•i•ty  (in′fən til′i tē), n.  Synonyms

• 1. puerile, immature, weak. See childish. 

Antonyms

• 1. adult, mature.

Collins Concise English Dictionary © HarperCollins Publishers::

infantile / ˈɪnfənˌtaɪl/ adjective

1. like a child in action or behaviour; childishly immature; puerile
2. of, relating to, or characteristic of infants or infancy
3. in an early stage of development

infantility / ˌɪnfənˈtɪlɪtɪ/ noun