proton

noun

pro·ton ˈprō-ˌtän

: an elementary particle that is identical with the nucleus of the hydrogen atom, that along with the neutron is a constituent of all other atomic nuclei, that carries a positive charge numerically equal to the charge of an electron, and that has a mass of 1.673 × 10⁻²⁷ kilogram

protonic

prō-ˈtä-nik

adjective

Examples of proton 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.

The other free-standing proton centers in Florida are in Naples and Jacksonville. — Cindy Krischer Goodman, Sun Sentinel, 28 Oct. 2026 The facility uses an accelerator to fire short proton pulses at a liquid mercury target. — Georgina Jedikovska, Interesting Engineering, 28 Oct. 2026 At the end of the chain, oxygen accepts the electrons and, together with protons, becomes water. — Rowan Jacobsen, Scientific American, 20 Oct. 2026 The protease partially pulls a proton off the water molecule, activating it to attack and break up the peptide bond. — ArsTechnica, 14 Oct. 2026 See All Example Sentences for proton

Word History

Etymology

Greek prōton, neuter of prōtos first — more at proto-

First Known Use

1920, in the meaning defined above

Time Traveler

The first known use of proton was in 1920

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Cite this Entry

Style

“Proton.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/proton. Accessed 1 Nov. 2026.

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Kids Definition

proton

noun

pro·ton ˈprō-ˌtän

: an atomic particle that occurs in the nucleus of every atom and carries a positive charge equal in size to the negative charge of an electron

protonic

prō-ˈtän-ik

adjective

Medical Definition

proton

noun

pro·ton ˈprō-ˌtän

: an elementary particle that is identical with the nucleus of the hydrogen atom, that along with neutrons is a constituent of all other atomic nuclei, that carries a positive charge numerically equal to the charge of an electron, and that has a mass of 1.673×10⁻²⁴ gram

protonic

prō-ˈtän-ik

adjective

proton

noun

Examples of proton in a Sentence

Word History

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Cite this Entry

Kids Definition

Medical Definition

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proton

noun

Examples of proton in a Sentence

Word History

Phrases Containing proton

Rhymes for proton

Browse Nearby Words

Cite this Entry

Kids Definition

Medical Definition

More from Merriam-Webster on proton

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