i-adjective
Describes a child or young animal; emphasizes tender age and innocence.
幼い子どもが公園で遊んでいる。
Very young children are playing in the park.
彼女は幼い頃からピアノを習
She has been learning piano since she was little.
i-adjective
Used for behavior, thinking, or appearance that seems immature for one's age; can be mildly critical.
そんな考え方は幼いと思う。
I think that way of thinking is childish.
彼は大人なのに、言動が幼い。
Although he is an adult, his words and actions are immature.