extraterrestrial

American  

[ek-struh-tuh-res-tree-uhl] / ˌɛk strə təˈrɛs tri əl /

adjective

1. outside, or originating outside, the limits of the earth.

   People on earth have long speculated about the idea of extraterrestrial life.

   Cataclysmic wildfires could be expected if earth were to take an extraterrestrial hit.

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noun

1. a being originating from beyond the earth; an alien from outer space.

   It was your typical sci-fi novel about extraterrestrials conquering the earth.

extraterrestrial British  

/ ˌɛkstrətɪˈrɛstrɪəl /

adjective

1. occurring or existing beyond the earth's atmosphere

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noun

1. (in science fiction) a being from beyond the earth's atmosphere

extraterrestrial Scientific  

/ ĕk′strə-tə-rĕs′trē-əl /

1. Originating, located, or occurring outside the Earth or its atmosphere.

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extraterrestrial Cultural  

1. A descriptive term for things outside the Earth, such as possible civilizations outside the solar system, or objects, such as meteorites, that actually reach the Earth.

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Other Word Forms

• extraterrestrially adverb

Etymology

Origin of extraterrestrial

First recorded in 1865–70; extra- + terrestrial

Explanation

Use the adjective extraterrestrial to describe anything that comes from or exists outside of the earth, like life on a distant planet, material from an asteroid, or even the sun. The word extraterrestrial makes most people think of big-headed green aliens in spaceships, and if you saw one you'd be right to describe it that way. But as both a noun and an adjective, the word is most often used by scientists to talk about anything — life, rocks, or environments on other planets — that happens outside of the earth's atmosphere. This makes sense when you know that in Latin, extra means "outside" and terra means "earth."

Example Sentences

Astronomers searching for extraterrestrial life have now identified the most promising places to look.

From Science Daily • Mar. 25, 2026

"Disclosure Day," Spielberg's return to extraterrestrial science fiction starring Emily Blunt and Josh O'Connor, is slated for release in June.

From Barron's • Mar. 14, 2026

When this extraterrestrial jetsam occasionally plunges through the atmosphere, it poses a risk to life, infrastructure and the environment.

From The Wall Street Journal • Jan. 23, 2026

But it does hint strongly at extraterrestrial visitors being revealed to humankind with a tagline: "If you found out we weren't alone, if someone showed you, proved it to you, would that frighten you?"

From BBC • Dec. 27, 2025

As with the search for extraterrestrial life today, the unbridled speculation of amateurs had frightened many professionals out of the field.

From "Cosmos" by Carl Sagan