queen

Definition:

A queen is either the female ruler of a country or the wife of a king.

Esther became the queen of the Persian empire when she married King Ahasuerus.
Queen Jezebel was the evil wife of King Ahab.
The Queen of Sheba was a famous ruler who came to visit King Solomon.
A term such as "queen mother" usually referred to the mother or grandmother of a ruling king or the widow of the previous king. A queen mother had much influence; Athaliah, for example, influenced the people to worship idols.