A woman who is not married, especially an older woman who is not likely to marry

The son of your brother or sister

(Formal or technical) a brother or sister

The brother of your husband or wife

(Formal or law) a husband or wife

The daughter of your brother or sister

The woman who is married to your father but who is not your real mother

The woman that a man is engaged to

The man that a woman is engaged to

A man who has never been married