The Collaborative International Dictionary of English v.0.48:

Dame \Dame\ (d[=a]m), n. [F. dame, LL. domna, fr. L. domina
   mistress, lady, fem. of dominus master, ruler, lord; akin to
   domare to tame, subdue. See Tame, and cf. Dam a mother,
   Dan, Danger, Dungeon, Dominie, Don, n., Duenna.]
   1. A mistress of a family, who is a lady; a woman in
      authority; especially, a lady.
      [1913 Webster]

            Then shall these lords do vex me half so much,
            As that proud dame, the lord protector's wife.
                                                  --Shak.
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   2. The mistress of a family in common life, or the mistress
      of a common school; as, a dame's school.
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            In the dame's classes at the village school.
      --Emerson.
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   3. A woman in general, esp. an elderly woman.
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   4. A mother; -- applied to human beings and quadrupeds.
      [Obs.] --Chaucer.
      [1913 Webster]

WordNet (r) 3.0 (2006):

dame
    n 1: informal terms for a (young) woman [syn: dame, doll,
         wench, skirt, chick, bird]
    2: a woman of refinement; "a chauffeur opened the door of the
       limousine for the grand lady" [syn: dame, madam, ma'am,
       lady, gentlewoman]