The Collaborative International Dictionary of English v.0.48:

Cyclops \Cy"clops\ (s?"kl?ps), n. sing. & pl. [L. Cyclops, Gr.
   Ky`klwps (strictly round-eyed), pl. Ky`klwpes; ky`klos circle
   + 'w`ps eye.]
   1. (Gr. Myth.) One of a race of giants, sons of Neptune and
      Amphitrite, having but one eye, and that in the middle of
      the forehead. They were fabled to inhabit Sicily, and to
      assist in the workshops of Vulcan, under Mt. Etna.
      [1913 Webster]

   Note: Pope, in his translation of the "Odyssey," uniformly
         spells this word Cyclop, when used in the singular.
         [1913 Webster]

   2. (Zool.) A genus of minute Entomostraca, found both in
      fresh and salt water. See Copepoda.
      [1913 Webster]

   3. A portable forge, used by tinkers, etc.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Cyclops
    n 1: (Greek mythology) one of a race of giants having a single
         eye in the middle of their forehead
    2: minute free-swimming freshwater copepod having a large median
       eye and pear-shaped body and long antennae used in swimming;
       important in some food chains and as intermediate hosts of
       parasitic worms that affect man e.g. Guinea worms [syn:
       cyclops, water flea]