Cyclops

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of the three one-eyed Titans who forged thunderbolts for Zeus.
• noun Any of a race of one-eyed giants, reputedly descended from these Titans, inhabiting the island of Sicily.

from The Century Dictionary.

• noun [lowercase] A monster having one imperfect eye, sometimes showing a fusion of two, near the middle line.
• noun Pl. Cyclopes (sī-klō′ pēz) or Cyclops. In Greek myth and legend: A giant with but one eye, which was circular and in the middle of the forehead.
• noun In the Odyssey, one of a race of gigantic, lawless cannibal shepherds in Sicily, under the one-eyed chief Polyphemus.
• noun One of a Thracian tribe of giants, named from a king Cyclops, who, expelled from their country, were fabled to have built in their wanderings the great prehistoric walls and fortresses of Greece. See cyclopean.
• noun In zoology, a genus of minute fresh-water copepods, typical of the family Cyclopidæ, having a greatly enlarged pair of antennules (the appendages of the second somite of the head), by the vigorous strokes of which they dart through the water as if propelled by oars.
• noun [lowercase] A copepod of the genus Cyclops.

from the GNU version of the Collaborative International Dictionary of English.

• noun (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.
• noun (Zoöl.) A genus of minute Entomostraca, found both in fresh and salt water. See Copepoda.
• noun A portable forge, used by tinkers, etc.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• proper noun A taxonomic genus within the family Cyclopidae — widespread, small, one-eyed, freshwater crustaceans.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun 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
• noun (Greek mythology) one of a race of giants having a single eye in the middle of their forehead