The Collaborative International Dictionary of English v.0.48:

Maid \Maid\, n. [Shortened from maiden. ?. See Maiden.]
   1. An unmarried woman; usually, a young unmarried woman;
      esp., a girl; a virgin; a maiden.
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            Would I had died a maid,
            And never seen thee, never borne thee son. --Shak.
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            Can a maid forget her ornaments, or a bride her
            attire? Yet my people have forgotten me. --Jer. ii.
                                                  32.
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   2. A man who has not had sexual intercourse. [Obs.]
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            Christ was a maid and shapen as a man. --Chaucer.
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   3. A female servant.
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            Spinning amongst her maids.           --Shak.
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   Note: Maid is used either adjectively or in composition,
         signifying female, as in maid child, maidservant.
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   4. (Zool.) The female of a ray or skate, esp. of the gray
      skate (Raia batis), and of the thornback (Raia
      clavata). [Prov. Eng.]
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   Fair maid. (Zool.) See under Fair, a.

   Maid of honor, a female attendant of a queen or royal
      princess; -- usually of noble family, and having to
      perform only nominal or honorary duties.

   Old maid. See under Old.
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WordNet (r) 3.0 (2006):

maid
    n 1: a female domestic [syn: maid, maidservant, housemaid,
         amah]
    2: an unmarried girl (especially a virgin) [syn: maid,
       maiden]

Moby Thesaurus II by Grady Ward, 1.0:

94 Moby Thesaurus words for "maid":
   abigail, amah, au pair girl, ayah, babe, baby, bachelor girl,
   betweenmaid, biddy, broad, chambermaid, chaperon, chick, colleen,
   companion, cook, cutie, daily, dame, damoiselle, damsel,
   demoiselle, doll, domestic, duenna, feme sole, femme de chambre,
   fille de chambre, filly, frail, gal, gentlewoman, girl, girlie,
   handmaid, handmaiden, heifer, hired girl, housemaid, hoyden,
   jeune fille, jill, junior miss, kitchenmaid, lady-help,
   lady-in-waiting, lass, lassie, little missy, live-in maid,
   live-out maid, lone woman, mademoiselle, maiden, maiden lady,
   maidservant, miss, missy, nursemaid, nymph, nymphet, old maid,
   parlormaid, piece, quail, romp, schoolgirl, schoolmaid, schoolmiss,
   scullery maid, servant girl, servitress, single girl, skirt, slip,
   soubrette, spinster, spinstress, subdeb, subdebutante, subteen,
   subteener, teenybopper, tomato, tomboy, tweeny, upstairs maid,
   vestal, vestal virgin, virgin, waiting maid, wench, young creature,
   young thing