Argus

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Greek Mythology A giant with 100 eyes who was made guardian of Io and was later slain by Hermes.
2. n. An alert or watchful person; a guardian.

Century Dictionary and Cyclopedia

1. n. In Grecian legend, a giant of vast strength, held in early times to have four eyes, and later to have eyes without number. Hera set him to guard the heifer Io, and after he was slain by Hermes transferred his eyes to the tail of the peacock.
2. n. Any observant or sharp-sighted person: as, he is a very Argus in watchfulness.
3. n. In ornithology: A genus of gallinaceous birds, of the order Gallinœ and family Phasianidœ, characterized by the enormous development of the secondary feathers of the wings and middle feathers of the tail, the former being adorned with numerous ocelli, likened to the many eyes of Argus. The type is the argus-pheasant (Phasianus argus, or Argus giganteus or pavoninus) of the Malay archipelago. Other species or varieties are the Argus grayi of Elliot, from Borneo, the Argus ocellatus of Verreaux, and the Argus bipunctatus. Other forms of the word, as a genus name, are Argusanus and Argusianus.
4. n. [lowercase] Any species of the genus Argus; an argus-pheasant. The common species has a body only about as large as that of a barnyard hen, but sometimes measures 5 or 6 feet in total length, owing to the extraordinary development of the tail-feathers. The inner feathers of the wing are 2 or 3 feet long, and beautifully ocellated with metallic iridescent spots. The general plumage is brown, variegated with lighter and darker tracery. The female is a plain bird, lacking the extraordinary development of the wing- and tail-feathers.
5. n. A genus of gastropods.
6. n. A genus of lepidopterous insects.
7. n. A genus of arachnidans.
8. n. [lowercase] A name of certain euryalean ophiurians, or sand-stars with branching arms.

Wiktionary

1. n. Greek mythology A fabulous being of antiquity, also called Argus Panoptes, said to have had a hundred eyes. His eyes were transplanted to the peacock’s tail. He was a servant of the greek goddess Hera.

GNU Webster's 1913

1. n. (Myth.) A fabulous being of antiquity, said to have had a hundred eyes, who has placed by Juno to guard Io. His eyes were transplanted to the peacock's tail.
2. n. One very vigilant; a guardian always watchful.
3. n. (Zoöl.) A genus of East Indian pheasants. The common species (Argus giganteus) is remarkable for the great length and beauty of the wing and tail feathers of the male. The species Argus Grayi inhabits Borneo.

WordNet 3.0

1. n. (Greek mythology) a giant with 100 eyes; was guardian of the heifer Io and was slain by Hermes
2. n. large brilliantly patterned East Indian pheasant