: 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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Phosphorus has two additional protons compared to aluminum and was formed when the alpha particles fused with the aluminum nuclei.
—
Andrea Richard, The Conversation, 2 Oct. 2025
Spencer underwent two surgeries, which lasted a combined 23 hours, and had proton beam therapy and nine months of chemotherapy.
—Escher Walcott, PEOPLE, 30 Sep. 2025
The next year, in 1920, Rutherford gave protons their name, teaching us what the two main components of atoms were.
—Ethan Siegel, Big Think, 30 Sep. 2025
But the shifts are subtle, so researchers turned to higher-order statistical tools that reveal changes in the shape of the proton distribution.
—Aamir Khollam, Interesting Engineering, 29 Sep. 2025
See All Example Sentences for proton
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Andrea Richard, The Conversation, 2 Oct. 2025
Spencer underwent two surgeries, which lasted a combined 23 hours, and had proton beam therapy and nine months of chemotherapy.
—Escher Walcott, PEOPLE, 30 Sep. 2025
The next year, in 1920, Rutherford gave protons their name, teaching us what the two main components of atoms were.
—Ethan Siegel, Big Think, 30 Sep. 2025
But the shifts are subtle, so researchers turned to higher-order statistical tools that reveal changes in the shape of the proton distribution.
—Aamir Khollam, Interesting Engineering, 29 Sep. 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 8 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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