Tomboy

from WordNet (r) 3.0 (2006)

tomboy
    n 1: a girl who behaves in a boyish manner [syn: {tomboy},
         {romp}, {hoyden}]

from The Collaborative International Dictionary of English v.0.48

Tomboy \Tom"boy`\, n. [Tom (for Thomas, L. Thomas, fr. Gr. ? )+
   boy.]
   A romping girl; a hoiden. [Colloq.] --J. Fletcher.
   [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

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