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antimatter

American  
[an-tee-mat-er, an-tahy-] / ˈæn tiˌmæt ər, ˈæn taɪ- /

noun

Physics.
  1. matter composed only of antiparticles, especially antiprotons, antineutrons, and positrons.


antimatter British  
/ ˈæntɪˌmætə /

noun

  1. a form of matter composed of antiparticles, such as antihydrogen, consisting of antiprotons and positrons

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

antimatter Scientific  
/ ăntĭ-măt′ər /
  1. A form of matter that consists of antiparticles.


antimatter Cultural  

Etymology

Origin of antimatter

First recorded in 1950–55; anti- + matter

Explanation

Antimatter is composed of antiparticles, which have the opposite charge of regular particles. Antimatter is also called negative matter. Matter makes up all the things that exist: everything in the world is matter. Words beginning with anti are opposed to their root. Therefore, antimatter is the opposite of matter. If antimatter and matter were to collide, both would be destroyed, releasing a huge and dangerous amount of energy. This happens because the particles that make up matter and the antiparticles that make up antimatter have opposite electric charges. The existence of antimatter is something studied by physicists.

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Vocabulary lists containing antimatter

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.

By combining their results, researchers can better study neutrinos and their antimatter counterparts, offering insight into why the universe did not self destruct immediately after the Big Bang.

From Science Daily • Mar. 3, 2026

Yet the observable universe is overwhelmingly made of matter, with very little antimatter remaining from the Big Bang.

From Science Daily • Mar. 3, 2026

When matter and antimatter meet, they annihilate each other in a burst of energy.

From Science Daily • Mar. 3, 2026

I think of this book as the antimatter to JD Vance’s “Hillbilly Elegy.”

From The Wall Street Journal • Dec. 12, 2025

My chest was about to explode, hurling matter and antimatter out until they annihilated everything nearby.

From "Darius the Great Is Not Okay" by Adib Khorram