puer ‧ ile /ˈpjʊəraɪl $ ˈpjʊrəl/ BrE AmE adjective formal
[ Date: 1500-1600 ; Language: French ; Origin: puéril , from Latin puerilis , from puer 'boy, child' ]
silly and stupid SYN childish :
a puerile joke
—puerility /pjʊˈrɪləti, pjʊˈrɪlɪti/ noun [uncountable]