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.
The study, published July 16 in Science, describes observations of helium escaping from LHS 1140 b, a rocky exoplanet located about 48 light-years from Earth.
From Science Daily ● Jul. 21, 2026
LHS 3844b is an exoplanet just slightly larger than Earth that orbits the red dwarf star LHS 3884, located 48.5 light years from our solar system.
From Science Daily ● Jul. 9, 2026
Most exoplanet discoveries to date have come from relatively nearby regions of the galaxy.
From Science Daily ● Jun. 1, 2026
"As we are seeing more and more different exoplanet systems, we are starting to revisit these theories."
From Science Daily ● May 21, 2026
To investigate these unusual systems, Kanodia, Cañas, and Jessica Libby-Roberts of the University of Tampa are leading JWST's largest Cycle 2 exoplanet program, Red Dwarfs and the Seven Giants.
From Science Daily ● Apr. 6, 2026
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
