(2 syl.). A sorceress. She lived in the island of Ææa. When Ulysses landed there, Circë turned his companions into swine, but Ulysses resisted this metamorphose by virtue of a herb called moly, given him by Mercury.
Who knows not Circe, The daughter of the Sun, whose charmëd cup Whoever tasted lost his upright shape, And downward fell into a grovelling swine?
Milton: Comus, 50- 53.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
More on Circe from Fact Monster: