pu·er·ile adj \ˈpyu̇(-ə)r-əl, -ˌīl\
: marked by or suggesting childishness and immaturity
: being respiration that is like that of a child in being louder than normal <puerile breathing>
Seen & Heard
What made you want to look up puerile? Please tell us where you read or heard it (including the quote, if possible).