Mistress meaning : A woman, specifically one with great control, authority or ownership A female teacher The other woman in an extramarital relationship, generally including sexual relations A dominatrix A woman well skilled in anything, or having the mastery over it A woman regarded with love and devotion; a sweetheart A married woman; a wife The jack in the game of bowls A female companion to a master (a man with control, authority or ownership) Of a woman: to master; to learn or develop to a high degree of proficiency. To act or take the role of a mistress.