Origin

In English, the word has come to mean "an embodiment, a bodily manifestation of the Divine." However, the Sanskrit word Avatara means "the descent of God" or simply "incarnation." The term is used primarily in Hindu texts. For example, Krishna is the eighth avatar (incarnation) of Vishnu the Preserver, whom many Hindus worship as God. The Dasavatara are ten particular "great" incarnations of Vishnu.
(wikipedia)


While Stephenson was not the first to apply the Sanskrit term avatar to online virtual bodies (the video game Habitat did that), the success of Snow Crash popularized the term to the extent that avatar is now the accepted term for this concept in computer games and on the World Wide Web.
(wikipedia)