extraterrestrial
n.a living creature that comes from a place outside of Earth, like another planet.
n.a hypothetical being originating from outside the Earth or its atmosphere.
“The movie is about a friendly extraterrestrial who gets lost on Earth.”
“Scientists use powerful telescopes to search for signals that might prove the existence of an extraterrestrial.”
“While popular culture often depicts an extraterrestrial as a humanoid figure, astrobiologists suggest that alien life is more likely to be microbial.”
Often used as an adjective to describe things related to outer space, but functions as a noun when referring to the being itself.
“Not only is there no evidence that extraterrestrials are trying to contact or visit us; there is no evidence that they exist at all.”
“That question is at the center of a new paper published in Nature Astronomy , where researchers examine the often-overlooked problem of "false negatives" in the search for extraterrestrial life.”
From extra- + terrestrial.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.