/uy"oh, ee"oh/ , n.
1. Class. Myth. a woman who, being loved by Zeus, was transformed into a white heifer and was, at the wish of Hera, first guarded by Argus and later pursued through the world by a gadfly until she reached Egypt, where she resumed her true shape: identified by the Egyptians with Isis.
2. Astron. a large volcanically active moon of the planet Jupiter.
/uy"oh, ee"oh/ , n. , pl. Ios .
See Io moth .
Symbol, Chem.
ionium.