noun
Refers to a woman in a position of authority or control, or a woman having an extramarital relationship with a man. Usage mirrors English 'mistress'.
彼は長年ミストレスと関係を持っていた。
He had a relationship with a mistress for many years.
その屋敷のミストレスは使用人たちに厳しかった。
The mistress of the mansion was strict with the servants.