The Collaborative International Dictionary of English v.0.48:

Damsel \Dam"sel\ (d[a^]m"z[e^]l), n. [OE. damosel, damesel,
   damisel, damsel, fr. OF. damoisele, damisele, gentlewoman, F.
   demoiselle young lady; cf. OF. damoisel young nobleman, F.
   damoiseau; fr. LL. domicella, dominicella, fem., domicellus,
   dominicellus, masc., dim. fr. L. domina, dominus. See Dame,
   and cf. Demoiselle, Doncella.]
   1. A young person, either male or female, of noble or gentle
      extraction; as, Damsel Pepin; Damsel Richard, Prince of
      Wales. [Obs.]
      [1913 Webster]

   2. A young unmarried woman; a girl; a maiden.
      [1913 Webster]

            With her train of damsels she was gone,
            In shady walks the scorching heat to shun. --Dryden.
      [1913 Webster]

            Sometimes a troop of damsels glad, . . .
            Goes by to towered Camelot.           --Tennyson.
      [1913 Webster]

   3. (Milling) An attachment to a millstone spindle for shaking
      the hopper.
      [1913 Webster]

WordNet (r) 3.0 (2006):

damsel
    n 1: a young unmarried woman [syn: damsel, demoiselle,
         damoiselle, damosel, damozel]

Moby Thesaurus II by Grady Ward, 1.0:

48 Moby Thesaurus words for "damsel":
   babe, baby, broad, chick, colleen, cutie, dame, damoiselle,
   demoiselle, doll, filly, frail, gal, girl, girlie, heifer, hoyden,
   jeune fille, jill, junior miss, lass, lassie, little missy,
   mademoiselle, maid, maiden, miss, missy, nymphet, piece, quail,
   romp, schoolgirl, schoolmaid, schoolmiss, skirt, slip, subdeb,
   subdebutante, subteen, subteener, teenybopper, tomato, tomboy,
   virgin, wench, young creature, young thing