Answer: io

AnswerCrossword Clue
iosmall hawk, Buteo solitarius, having two plumage phases and occurring only on the island of Hawaii, where it is a rare species and the only living indigenous bird of prey
ioshowy, yellow moth, Automeris io, of North America, having a prominent pink and bluish eyespot on each hind wing
iolarge volcanically active moon of the planet Jupiter
ioa maiden loved by Zeus and changed by him into a heifer so that she might escape the jealous rage of Hera
ioa cry of joy
iowoman 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
ioionium