: 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
Examples of proton in a Sentence
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This inferno re-creates conditions from the dawn of time, when the universe was too hot and dense to form regular atoms—or even their ingredients such as protons and neutrons.
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Clara Moskowitz, Scientific American, 15 Nov. 2025
Steven Garcia / Reuters A CME is an eruption of massive clouds of protons, electrons and magnetic fields from the sun’s outer atmosphere at very high speeds.
—Mithil Aggarwal, NBC news, 12 Nov. 2025
While in this energized state, the lignin functions as a photoacid, transferring protons to the histidine inside the solid material.
—Mrigakshi Dixit, Interesting Engineering, 10 Nov. 2025
These frequencies, Weber argued, had to be large, as gravitational waves passing through them would only induce a size change of a fraction-of-a-proton’s width.
—Big Think, 7 Nov. 2025
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Clara Moskowitz, Scientific American, 15 Nov. 2025
Steven Garcia / Reuters A CME is an eruption of massive clouds of protons, electrons and magnetic fields from the sun’s outer atmosphere at very high speeds.
—Mithil Aggarwal, NBC news, 12 Nov. 2025
While in this energized state, the lignin functions as a photoacid, transferring protons to the histidine inside the solid material.
—Mrigakshi Dixit, Interesting Engineering, 10 Nov. 2025
These frequencies, Weber argued, had to be large, as gravitational waves passing through them would only induce a size change of a fraction-of-a-proton’s width.
—Big Think, 7 Nov. 2025
See All Example Sentences for proton
Cite this Entry
“Proton.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/proton. Accessed 25 Nov. 2025.
Copy CitationKids 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
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
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