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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
This is akin to what happens when an electron meets its antimatter counterpart, or positron. — Robert Lea, Space.com, 21 June 2026 The theory cannot account for dark matter and offers no explanation for why the universe is made almost entirely of matter rather than equal parts matter and antimatter. — Florencia Canelli, Scientific American, 1 July 2026 Matter is so dominant in our universe that any antimatter typically encounters matter quickly and annihilates. — Quanta Magazine, 15 June 2026 Recently, the SpaceX founder and CEO shared a new prediction about antimatter propulsion on the social media platform X and received overwhelming support. — Ameya Paleja, Interesting Engineering, 23 June 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

Rhymes for antimatter

See All Rhymes for antimatter

Browse Nearby Words

anti-materialism
antimatter
antimechanized
See all Nearby Words

Cite this Entry

“Antimatter.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/antimatter. Accessed 10 Jul. 2026.

Copy Citation

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)

More from Merriam-Webster on antimatter

Britannica.com: Encyclopedia article about antimatter

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Popular in Grammar & Usage

See More

Is that lie 'bald-faced' or 'bold-faced'?

'A' or 'an'? What about before 'h'? An Indefinite Article Guide

Why is '-ed' sometimes pronounced at the end of a word?

Commonly Misspelled Words

How to Use Em Dashes (—), En Dashes (–) , and Hyphens (-)
See More

Popular in Wordplay

See More

14 Phobias You Probably Haven't Heard Of

The Longest Long Words List

One-Word Oxymorons: Bittersweet, Spendthrift, and More

Ten Words Ending with a Silent ‘T’

The Words of the Week - Jul 10
See More

Popular

See More

Is that lie 'bald-faced' or 'bold-faced'?

14 Phobias You Probably Haven't Heard Of

The Longest Long Words List
See More

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
The Missing Letter A daily crossword with a twist
hangman letters and game
Hangman Lightning Round Figure out which word fits in the blanks.
See All