Mis·tress n.
 1. A woman having power, authority, or ownership; a woman who exercises authority, is chief, etc.; the female head of a family, a school, etc.
 The late queen's gentlewoman! a knight's daughter!
 To be her mistress' mistress!   --Shak.
 2. A woman well skilled in anything, or having the mastery over it.
    A letter desires all young wives to make themselves mistresses of Wingate's Arithmetic.   --Addison.
 3. A woman regarded with love and devotion; she who has command over one's heart; a beloved object; a sweetheart. [Poetic]
 4. A woman filling the place, but without the rights, of a wife; a woman having an ongoing usually exclusive sexual relationship with a man, who may provide her with financial support in return; a concubine; a loose woman with whom one consorts habitually; as, both his wife and his mistress attended his funeral.
 5. A title of courtesy formerly prefixed to the name of a woman, married or unmarried, but now superseded by the contracted forms, Mrs., for a married, and Miss, for an unmarried, woman.
    Now Mistress Gilpin (careful soul).   --Cowper.
 6. A married woman; a wife. [Scot.]
    Several of the neighboring mistresses had assembled to witness the event of this memorable evening.   --Sir W. Scott.
 7. The old name of the jack at bowls.
 To be one's own mistress, to be exempt from control by another person.