adopted son
A son who has been legally adopted into a family. The term is straightforward and neutral.
He is an adopted son, but he was raised like a biological child.
Standard mixed kanji-kana spelling.
Full kanji spelling with 貰う; less common in modern writing.
Compound of もらい (receiving) from 貰う (to receive) and 息子 (son). The term literally means 'received son'.