What does 幼い mean?
幼い is a Japanese adjective meaning “very young, childish” in English. It can also be translated as “childish” depending on context. It is written as 幼い in kanji, おさない in hiragana, and osanai in romaji. This word is part of JLPT N3 vocabulary.
Example sentence
その幼い少年は父親の両肩の上に乗っていた。
The little boy sat on his father's shoulders.