Cyclops

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Greek Mythology Any of the three one-eyed Titans who forged thunderbolts for Zeus.
2. n. Greek Mythology Any of a race of one-eyed giants, reputedly descended from these Titans, inhabiting the island of Sicily.

Century Dictionary and Cyclopedia

1. n. 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. According to the Hesiodic legend, there were three Cyclopes of the race of Titans, sons of Uranns and Ge, who forged the thunderbolts of Zeus, Pluto's helmet, and Poseidon's trident, and were considered the primeval patrons of all smiths. Their workshops were afterward said to be under Mount Etna.
2. n. In the Odyssey, one of a race of gigantic, lawless cannibal shepherds in Sicily, under the one-eyed chief Polyphemus.
3. n. 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.
4. n. 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. In the front of the head there is a beady black median eye, really double, but appearing single, whence the name of the genus. Cyclops quadricornis is a common water-flea of fresh-water ponds and ditches. See Copepoda.
5. n. [lowercase] A copepod of the genus Cyclops.
6. n. [lowercase] A monster having one imperfect eye, sometimes showing a fusion of two, near the middle line.

Wiktionary

1. n. A taxonomic genus within the family Cyclopidae — widespread, small, one-eyed, freshwater crustaceans.

GNU Webster's 1913

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

WordNet 3.0

1. n. 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
2. n. (Greek mythology) one of a race of giants having a single eye in the middle of their forehead