: 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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But when protons raced both ways around the tunnel and crashed head-on, spraying debris into surrounding detectors, only the 25 particles of the Standard Model were observed.
—
Quanta Magazine, 26 Jan. 2026
During this storm, some space weather forecasters reported temporary data dropouts, likely caused by intense proton fluxes degrading spacecraft measurements.
—Daisy Dobrijevic, Space.com, 20 Jan. 2026
Researchers found that, at five years, survival rates among patients who received proton therapy were 10% higher.
—Jillian Taylor, StateImpact, 20 Jan. 2026
Acidic moisture increased voltage significantly, as protons act as efficient charge carriers.
—Prabhat Ranjan Mishra, Interesting Engineering, 5 Jan. 2026
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Quanta Magazine, 26 Jan. 2026
During this storm, some space weather forecasters reported temporary data dropouts, likely caused by intense proton fluxes degrading spacecraft measurements.
—Daisy Dobrijevic, Space.com, 20 Jan. 2026
Researchers found that, at five years, survival rates among patients who received proton therapy were 10% higher.
—Jillian Taylor, StateImpact, 20 Jan. 2026
Acidic moisture increased voltage significantly, as protons act as efficient charge carriers.
—Prabhat Ranjan Mishra, Interesting Engineering, 5 Jan. 2026
See All Example Sentences for proton
Cite this Entry
“Proton.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/proton. Accessed 30 Jan. 2026.
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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