Meaning of Io in English:

proper noun

• 1Greek Mythology
  A priestess of Hera who was loved by Zeus. Trying to protect her from the jealousy of Hera, Zeus turned Io into a heifer. Hera sent a gadfly to torture the heifer, which then fled across the world and finally reached Egypt, where Zeus turned her back into human form.

• 2Astronomy
  One of the Galilean moons of Jupiter, the fifth-closest satellite to the planet, being actively volcanic and coloured red and yellow with sulphur compounds (diameter 3,630 km).