puerile
🇺🇸
/ˈpjʊrəl/
🇬🇧
/ˈpjʊəraɪl/
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.
그의 유치한 행동은 공식 만찬에서 보기에 부끄러웠다.