childish

UK: /ˈtʃaɪldɪʃ/ US: /ˈtʃaɪldɪʃ/ ,(chīl′dish)

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

child•ish /ˈtʃaɪldɪʃ/   adj. 

1. immature;
   babyish:
   Don't be so childish; stop pouting and whining.
2. of or relating to a child or children:
   a childish face.
child•ish•ly, adv.: 
Stop behaving so childishly; grow up!

child•ish•ness, n. 
[uncountable] Stop your childishness at once.

WordReference Random House Unabridged Dictionary of American English © 2025

child•ish  (chīl′dish), adj. 

1. of, like, or befitting a child:
   childish games.
2. puerile;
   weak;
   silly:
   childish fears.

• Middle English childisch, Old English cildisc. See child, -ish¹ bef. 1000

child′ish•ly, adv. 
child′ish•ness, n. 
Synonyms

Childish, infantile, childlike refer to characteristics or qualities of childhood. The ending -ish often has unfavorable connotations; childish therefore refers to characteristics that are undesirable and unpleasant:
childish selfishness, outbursts of temper.
Infantile, originally a general word, now often carries an even stronger idea of disapproval or scorn than does childish:
infantile reasoning, behavior.
The ending -like has pleasing or neutral connotations; childlike therefore refers to the characteristics that are desirable and admirable:
childlike innocence, trust.

Antonyms

mature, adult.

Collins Concise English Dictionary © HarperCollins Publishers::

childish / ˈtʃaɪldɪʃ/ adjective

1. in the manner of, belonging to, or suitable to a child
2. foolish or petty; puerile: childish fears

ˈchildishly adverb

ˈchildishness noun