noun
adopted daughter
Refers to a girl or young woman who has been taken in and raised as one's own daughter, not necessarily through formal adoption.
彼女は幼い頃にもらい娘として育てられた。
She was raised as an adopted daughter from a young age.
養女 is a more formal or legal term for an adopted daughter, while もらい娘 is a warmer, more colloquial expression.
Compound of もらい (receiving) and 娘 (daughter), literally 'received daughter'.