The Collaborative International Dictionary of English v.0.48:

Colleen \Col*leen"\, n. [Ir. cailin.]
   A girl; a maiden. [Anglo-Irish]

         Of all the colleens in the land
         Sweet Mollie is the daisy.               --The Century.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

colleen
    n 1: an Irish girl

Moby Thesaurus II by Grady Ward, 1.0:

47 Moby Thesaurus words for "colleen":
   babe, baby, broad, chick, cutie, dame, damoiselle, damsel,
   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, romp,
   schoolgirl, schoolmaid, schoolmiss, skirt, slip, subdeb,
   subdebutante, subteen, subteener, teenybopper, tomato, tomboy,
   virgin, wench, young creature, young thing