adjective

infantile

infantile, childish, immature

His infantile behavior is not appropriate for his age.

His infantile behaviour is not appropriate for his age.

The patient showed signs of infantile regression.

The patient showed signs of infantile regression.

infantile ((noun)) childish, immature His infantile behavior is not appropriate.

Synonyms: childish, juvenile, immature; Antonyms: mature, adult

From Latin 'infantilis', from 'infans' (infant, one who cannot speak), from 'in-' (not) + 'fari' (to speak).

Think of an 'infant' acting in a silly way. The word describes behaviour that is like that of an infant.

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