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.
4. A woman filling the place, but without the rights, of a wife; a concubine; a loose woman with whom one consorts habitually.
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 A title of courtesy formerly prefixed to the name of a woman, married or unmarried, but now superseded by the contracted forms, Mrs, for a married, and miss, for an unmarried, woman.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. 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.
Origin: OE. Maistress, OF. Maistresse, F. Maitresse, LL. Magistrissa, for L. Magistra, fem. Of magister. See Master, Mister, and cf. Miss a young woman.