Io

Io

Io¹ [ī′ō΄; ] for 2, also [ ē′ō΄]

n.

[L < Gr Iō]

1. Gr. Myth. a maiden loved by Zeus and changed into a heifer by jealous Hera or, in some tales, by Zeus to protect her: she is watched by Argus and is driven to Egypt, where she regains human form

2. the third largest satellite of Jupiter: discovered in 1610 by Galileo and found in 1979 to be volcanically active

Io²

Chem.

symbol

ionium