antimatter

noun

an·​ti·​mat·​ter ˈan-tē-ˌma-tər How to pronounce antimatter (audio) ˈan-ˌtī- How to pronounce antimatter (audio)
: matter composed of antiparticles

Examples of antimatter in a Sentence

Recent Examples on the Web
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According to Fermilab, the project could help answer some of the biggest physics mysteries, including why matter dominates over antimatter in the universe and how the universe evolved after the Big Bang. Georgina Jedikovska, Interesting Engineering, 8 May 2026 That could mean that, even in a best-case scenario, DUNE won’t determine the mass ordering of neutrinos until 2034—and any answer to the question of matter-antimatter imbalance wouldn’t arrive until the end of that decade. Joseph Howlett, Scientific American, 8 May 2026 That gamma ray would transform into an electron and its antimatter twin, a positron. Quanta Magazine, 6 May 2026 The usability of energy derived from matter-antimatter annihilation. Big Think, 22 Apr. 2026 See All Example Sentences for antimatter

Word History

First Known Use

1934, in the meaning defined above

Time Traveler
The first known use of antimatter was in 1934

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Cite this Entry

“Antimatter.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/antimatter. Accessed 13 May. 2026.

Kids Definition

antimatter

noun
an·​ti·​mat·​ter ˈant-i-ˌmat-ər How to pronounce antimatter (audio)
: matter whose parts match parts of ordinary matter except in having some opposite properties (as a positive instead of a negative charge)

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