E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Three of the sons of Urnus were so called, viz. Ægæon or Briareus [Bri-a-ruce], Kottos, and Gygs or Gys. Called in Greek
Hekatogcheiros [hek-ka-ton-kiros]. After the war between Zeus and the Titans, when the latter were overcome and hurled into Tartarus, the Hundred-handed ones were set to keep watch and ward over them. (See GIANTS.)
Sometimes the three-headed Cerberus is so called, because the necks were covered with snakes instead of hair.