puerile
🇺🇸
/ˈpjʊrəl/
🇬🇧
/ˈpjʊəraɪl/
adjective
R
acting like a child in a way that is not suitable for an adult
His puerile behavior at the formal dinner was embarrassing to watch.
フォーマルディナーでの彼の幼稚な行動は見ていて恥ずかしかった。
translation
子供じみた