n.
Pronunciation: ' in-f ə n- ˌ t ī - ˌ li-z ə m, -t ə - ˌ li-; in- ' fan-t ə - ˌ li-
Function: noun
Date: 1895
1 : retention of childish physical, mental, or emotional qualities in adult life especially : failure to attain sexual maturity
2 : an act or expression that indicates lack of maturity