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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.

Keep Reading on Vocabulary.com

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.

In simple terms, neutrinos may not behave exactly like their antimatter counterparts.

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

Each particle of matter has an antimatter partner with the same mass but opposite charge, and when they meet, they annihilate into pure energy.

From Science Daily • Dec. 7, 2025

These very massive, elusive particles then decayed into lighter, more stable particles with a slight preference for matter over antimatter.

From Science Daily • Dec. 7, 2025

We therefore believe that all galaxies are composed of quarks rather than antiquarks; it seems implausible that some galaxies should be matter and some antimatter.

From "A Brief History of Time: And Other Essays" by Stephen Hawking