mistress

n. 1 female head of a household. 2 a woman in authority. B female owner of a pet. 3 female teacher. 4 woman having an illicit sexual relationship with a (usu. Married) man. [french maistre *master, *-ess]

n. A woman having power, authority, or ownership; a woman who exercises authority, is chief, etc.; the female head of a family, a school, etc.