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

• extraterrestrials
  plural

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

Derived Forms

• extraterrestrially
  adverb

Inflected Forms

Nouns

• extraterrestrials
  plural

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

See Examples For:

extraterrestrial extraterrestrials

For K2-18b, only 6.6% of surveyed astrobiologists agreed that scientists had probably found extraterrestrial life.

From Science Daily ● Sep. 9, 2026

Second, though “virtually all scientists” reject the idea that aliens have visited Earth, researchers are “increasingly confident that humanity will discover extraterrestrial life.”

From The Wall Street Journal ● Aug. 28, 2026

He’s not a super-scientist or a god or an extraterrestrial or a one-percenter able to develop all manner of nifty crime-fighting gadgetry.

From Los Angeles Times ● Aug. 4, 2026

However, the authors note that this choice could also have excluded some genuinely weak extraterrestrial signals.

From Science Daily ● Jul. 14, 2026

How would we explain the global arms race to a dispassionate extraterrestrial observer?

From "Cosmos" by Carl Sagan

He doubts the existence of extraterrestrials but recognizes their prominence in our imagination as a chapter in “humanity’s evolving self-portrait.”

From The Wall Street Journal ● Aug. 28, 2026

At the end of Season 1, their cover being blown, and humans being famously weird when it comes to extraterrestrials — you’ve seen the movies — they return home en masse, except for Sugar.

From Los Angeles Times ● Jun. 19, 2026

In the movie, Blunt plays Margaret Fairchild, a TV meteorologist chosen by extraterrestrials as the human through whom they communicate—“the last person on earth that you’d imagine would be destined for this task,” Blunt says.

From The Wall Street Journal ● Jun. 4, 2026

In a follow-up post on Instagram, Obama, who served as US president between 2009-17, clarified: "I saw no evidence during my presidency that extraterrestrials have made contact with us. Really!"

From BBC ● Feb. 19, 2026

It would be easy for extraterrestrials to make an unambiguously artificial interstellar message.

From "Cosmos" by Carl Sagan