Definitions

1. noun

A moon of Jupiter, discovered in 1610. It is the second-largest moon in the solar system.

“The astronomer studied the geology of Callisto, noting its unique features.”

2. proper noun

Callisto, a figure in Greek and Roman mythology, the nymph who was transformed into a bear and subsequently became a constellation.

“In the ancient myth, Callisto was placed among the stars as the constellation Ursa Major.”