: 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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In 1932, Ioffe’s student Dmitrii Ivanenko came up with the neutron-proton model of the atom.
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Literary Hub, 23 Oct. 2025
However, the nuclei of some atoms of hydrogen feature one proton and one neutron, too.
—Keith Cooper, Space.com, 17 Oct. 2025
Unlike solar protons, these high-energy particles are nearly impossible to block completely and may significantly increase cancer risks over the years.
—Kaif Shaikh, Interesting Engineering, 16 Oct. 2025
And that each electron is tiny in mass compared to each proton, neutrons, and atomic nucleus.
—Big Think, 16 Oct. 2025
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Literary Hub, 23 Oct. 2025
However, the nuclei of some atoms of hydrogen feature one proton and one neutron, too.
—Keith Cooper, Space.com, 17 Oct. 2025
Unlike solar protons, these high-energy particles are nearly impossible to block completely and may significantly increase cancer risks over the years.
—Kaif Shaikh, Interesting Engineering, 16 Oct. 2025
And that each electron is tiny in mass compared to each proton, neutrons, and atomic nucleus.
—Big Think, 16 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 29 Oct. 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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