The Collaborative International Dictionary of English v.0.48:

Pixy \Pix"y\, Pixie \Pix"ie\, n.; pl. Pixies. [For Pucksy,
   from Puck.]
   1. An old English name for a fairy; an elf. [Written also
      picksy.]
      [1913 Webster]

   2. (Bot.) A low creeping evergreen plant (Pyxidanthera
      barbulata), with mosslike leaves and little white
      blossoms, found in New Jersey and southward, where it
      flowers in earliest spring.
      [1913 Webster]

   Pixy ring, a fairy ring or circle. [Prov. Eng.]

   Pixy stool (Bot.), a toadstool or mushroom. [Prov. Eng.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

pixie
    n 1: (folklore) fairies that are somewhat mischievous [syn:
         elf, hob, gremlin, pixie, pixy, brownie, imp]
    2: creeping evergreen shrub having narrow overlapping leaves and
       early white star-shaped flowers; of the pine barrens of New
       Jersey and the Carolinas [syn: pyxie, pixie, pixy,
       Pyxidanthera barbulata]

Moby Thesaurus II by Grady Ward, 1.0:

86 Moby Thesaurus words for "pixie":
   Ariel, Befind, Corrigan, Dingbelle, Fifinella, Finnbeara, Hob,
   Hobgoblin, Mab, Oberon, Puck, Titania, antic, bad boy, bad fairy,
   bad peri, banshee, booger, brownie, buffoon, bugger, cluricaune,
   coltish, cutup, devil, deviling, devilkin, diablotin, dwarf, elf,
   elvish, enfant terrible, erlking, fairy, fairy queen, fay,
   funmaker, gamesome, gnome, goblin, gremlin, hob, hood, hoodlum,
   hooligan, imp, impish, joker, jokester, knave, kobold, leprechaun,
   little devil, little monkey, little rascal, minx, mischief,
   mischief-maker, ouphe, peri, pixieish, pixilated, poltergeist,
   pooka, practical joker, prankish, prankster, puca, puck, puckish,
   pwca, rapscallion, rascal, rogue, rowdy, ruffian, scalawag, scamp,
   scapegrace, slyboots, sprite, sylph, sylphid, tokoloshe, wag,
   young devil