: 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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For example, technologies like proton beams, originally used in particle physics, are now being used for cancer treatment.
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Robert Lea, Space.com, 31 Oct. 2025
On the one hand, there would be double-neutrino double-beta decay, where the parent nucleus would emit two electrons and two neutrinos, transforming two of the neutrons in the nucleus into protons in the process.
—Big Think, 28 Oct. 2025
Gluons carry the strong nuclear force, which glues together fundamental particles called quarks to make protons and neutrons.
—Stephanie Pappas, Scientific American, 27 Oct. 2025
In 1932, Ioffe’s student Dmitrii Ivanenko came up with the neutron-proton model of the atom.
—Literary Hub, 23 Oct. 2025
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Robert Lea, Space.com, 31 Oct. 2025
On the one hand, there would be double-neutrino double-beta decay, where the parent nucleus would emit two electrons and two neutrinos, transforming two of the neutrons in the nucleus into protons in the process.
—Big Think, 28 Oct. 2025
Gluons carry the strong nuclear force, which glues together fundamental particles called quarks to make protons and neutrons.
—Stephanie Pappas, Scientific American, 27 Oct. 2025
In 1932, Ioffe’s student Dmitrii Ivanenko came up with the neutron-proton model of the atom.
—Literary Hub, 23 Oct. 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 4 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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