exoplanet
Americannoun
noun
Other Word Forms
Etymology
Origin of exoplanet
Explanation
An exoplanet is a planet that revolves around a different sun than ours. Sometimes a pizza takes so long to be delivered, you think it must be coming from one of the furthest known exoplanets! In the 1970s, when space science was taking off, the word exoplanet was invented by attaching the combining form exo-, meaning "outside," to the word planet. That English form exo- comes from the Greek, also meaning "outside," and is used in this case because the planet is outside our solar system. Exoskeleton is another word that uses this combining form, and refers to the hard supporting structure found on the outside of certain animals such as insects and crabs.
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
In 1855, British astronomer William Jacob proposed that the system contained a planet, making it the first star system to host an officially proposed exoplanet candidate.
From Science Daily ● Oct. 30, 2026
The team expects future observations using multiple wavelengths and similarly precise instruments to uncover a wider range of elements in exoplanet atmospheres.
From Science Daily ● Oct. 14, 2026
How can you tell if an exoplanet has an atmosphere?
From Science Daily ● Oct. 7, 2026
That added sensitivity could help astronomers discover more planets during their earliest stages of formation and close one of the biggest observational gaps in exoplanet science.
From Science Daily ● Sep. 17, 2026
A genuine signal from the exoplanet would appear only in the beam pointed at K2-18b, while interference from Earth would generally show up across multiple beams at the same time.
From Science Daily ● Jul. 14, 2026
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