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.
      [1913 Webster]

   2. The mistress of a family in common life, or the mistress
      of a common school; as, a dame's school.
      [1913 Webster]

            In the dame's classes at the village school.
      --Emerson.
      [1913 Webster]

   3. A woman in general, esp. an elderly woman.
      [1913 Webster]

   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]

Moby Thesaurus II by Grady Ward, 1.0:

133 Moby Thesaurus words for "dame":
   Eve, Frau, Fraulein, Jane, Miss, Mistress, Mlle, Mme, Mmes, abbess,
   archduchess, babe, baby, baroness, beldam, biddy, bird, bitch,
   broad, chatelaine, chick, colleen, countess, crone, cutie,
   damoiselle, damsel, daughter of Eve, demoiselle, distaff, doll,
   domina, dona, donna, dowager, duchess, duenna, educatress, femme,
   filly, first lady, frail, frow, frump, gal, gentlewoman, girl,
   girlie, goodwife, governess, grand duchess, grandam, grandmother,
   granny, great lady, hag, heifer, hen, homemaker, housewife, hoyden,
   instructress, jeune fille, jill, junior miss, khanum, lady, lass,
   lassie, little missy, madam, madame, mademoiselle, maid, maiden,
   marchioness, margravine, matriarch, matron, mem-sahib, mesdames,
   milady, minx, miss, missy, mistress, mother superior, noblewoman,
   nymphet, old battle-ax, old dame, old girl, old granny, old lady,
   old trot, old wife, old woman, peeress, piece, romp, schooldame,
   schoolgirl, schoolmaid, schoolmarm, schoolmiss, schoolmistress,
   senhora, senhorita, signora, signorina, skirt, slip, squaw, subdeb,
   subdebutante, subteen, subteener, teenybopper, tomato, tomboy,
   trot, tutoress, virgin, viscountess, vrouw, wahine, war-horse,
   weaker vessel, wench, witch, woman, young creature, young thing