: a subatomic particle identical to another subatomic particle in mass but opposite to it in electric and magnetic properties (such as sign of charge) that when brought together with its counterpart produces mutual annihilation
especially
: a subatomic particle not found in ordinary matter
Examples of antiparticle in a Sentence
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The end of whatever state came before the Big Bang (likely cosmic inflation) gave rise to a Universe full of particles, antiparticles, radiation, and all the ingredients necessary to make our existence possible.
—
Big Think, 27 Nov. 2025
When a particle encounters its antiparticle, the two annihilate each other in a burst of energy.
—Alexey A. Petrov, The Conversation, 25 Nov. 2025
Understanding neutrinos’ properties could help explain how how the universe formed, how stars evolve and whether neutrinos, which pass through the Earth and even our bodies like phantoms, are their own antiparticles.
—Georgina Jedikovska, Interesting Engineering, 8 Oct. 2025
However, three astrophysicists consider an alternative source of energy that may apply at the very center of our galaxy— energy released when dark matter particles and antiparticles collide and annihilate.
—ArsTechnica, 16 July 2025
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Big Think, 27 Nov. 2025
When a particle encounters its antiparticle, the two annihilate each other in a burst of energy.
—Alexey A. Petrov, The Conversation, 25 Nov. 2025
Understanding neutrinos’ properties could help explain how how the universe formed, how stars evolve and whether neutrinos, which pass through the Earth and even our bodies like phantoms, are their own antiparticles.
—Georgina Jedikovska, Interesting Engineering, 8 Oct. 2025
However, three astrophysicists consider an alternative source of energy that may apply at the very center of our galaxy— energy released when dark matter particles and antiparticles collide and annihilate.
—ArsTechnica, 16 July 2025
See All Example Sentences for antiparticle
Cite this Entry
“Antiparticle.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/antiparticle. Accessed 19 Dec. 2025.
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antiparticle
noun
an·ti·par·ti·cle
ˈant-i-ˌpärt-i-kəl 
ˈan-ˌtī-
: an elementary particle identical to another elementary particle in mass but opposite to it in electric or magnetic properties
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