Extraterrestrial: Etymology, Usage, and the Debate Over Life Beyond Earth

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Extraterrestrial means anything from outside the Earth or its atmosphere and can refer to a being from another world, used as both an adjective and a noun, and it is widely discussed in science and popular culture, including debates led by Harvard's Loeb and the Galileo Project about real extraterrestrials.

Definition of EXTRATERRESTRIAL
merriam-webster.com

Definition of EXTRATERRESTRIAL

originating, existing, or occurring outside the earth or its atmosphere… See the full definition