puerile

/ˈpjuːəraɪl/
adjective
  1. Childish and silly; showing a lack of maturity or good judgment.
    • His puerile jokes annoyed the entire class.
    • She refused to engage in such puerile arguments.
    • The debate turned puerile when they started name-calling.
Antonyms
What does "puerile" mean? | whatsthatwordmean | whatsthatwordmean