: 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
Recent Examples on the Web
This process often causes the element to change into another element, since the nucleus can lose protons.
—
Benjamin Roulston, The Conversation, 14 Mar. 2025
For years, the cosmic ray subsystem’s three-telescope array observed fluctuations from protons and other deep space energies, and was integral in determining when and where Voyager 1 exited the heliosphere.
—Andrew Paul, Popular Science, 5 Mar. 2025
That tells researchers that dark matter can't be made of atoms like everyday matter is, because the particles that comprise atoms — electrons, protons, and neutrons — do interact with light.
—Robert Lea, Space.com, 28 Feb. 2025
Doctors there, working in conjunction with a team an hour’s drive away at Beaumont Hospital in Royal Oak, drew up an initial treatment plan of chemotherapy and proton therapy.
—Rachel Clarke, CNN, 25 Feb. 2025
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Benjamin Roulston, The Conversation, 14 Mar. 2025
For years, the cosmic ray subsystem’s three-telescope array observed fluctuations from protons and other deep space energies, and was integral in determining when and where Voyager 1 exited the heliosphere.
—Andrew Paul, Popular Science, 5 Mar. 2025
That tells researchers that dark matter can't be made of atoms like everyday matter is, because the particles that comprise atoms — electrons, protons, and neutrons — do interact with light.
—Robert Lea, Space.com, 28 Feb. 2025
Doctors there, working in conjunction with a team an hour’s drive away at Beaumont Hospital in Royal Oak, drew up an initial treatment plan of chemotherapy and proton therapy.
—Rachel Clarke, CNN, 25 Feb. 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 22 Mar. 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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