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

Plus, a Chinese robot beat the human half-marathon record and the hunt for extraterrestrial life gets an update.

From The Wall Street Journal • Apr. 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

“We’re gonna have superstars, superheroes, and there is also going to be an extraterrestrial on the stage, so you can figure that one out,” Mullan said.

From Los Angeles Times • Mar. 11, 2026

US President Donald Trump says he will direct US agencies, including the defence department, to "begin the process of identifying and releasing" government files on aliens and extraterrestrial life.

From BBC • Feb. 19, 2026

“You won’t be mad at me if I use my extraterrestrial powers?”

From "Boy21" by Matthew Quick