(Δάειρα or Δαῖρα), that is, "the knowing," a divinity connected with the Eleusinian mysteries. According to Pausanias (1.38.7) she was a daughter of Oceanus, and became by Hermes the mother of Eleusis; but others called her a sister of Styx; while a third account represents her as identical with Aphrodite, Demeter, Hera, or Persephone. (Apollon. 3.847; Eustath, ad Hom. p. 648.)
[L.S]A Dictionary of Greek and Roman biography and mythology
Smith, William
A Dictionary of Greek and Roman biography and mythology. William Smith, LLD, ed. 1890