Definition: Something outside the limits of the earth.
Origins: The first person who was recorded using the word ”extraterrestrial” was H.G. Wells and, perhaps, he even invented the term around the turn of the century. L. Sprague de Camp, an American author, used the word as a noun in the May 1939 issue of Astounding Science Fiction. He invented the abbreviation “e.t.” in the same article. Steven Spielberg helped to cement the abbreviation with his famous 1982 science fiction film, E.T.
Hendrickson, Robert. Words and Phrase Origins. 3rd ed. New York: Facts On File, 2004, 249.