act childishly

verb phrase

Meaning

Behaving in a way that is immature, silly, or like a child, often in a way that is inappropriate for an adult.

Examples

  • He started to act childishly when he didn't get his way.
  • Please don't act childishly; we need to have a serious discussion.

Synonyms: behave immaturely, behave like a child, behave petulantly, behave puerilely