proton

noun

pro·​ton ˈprō-ˌtän How to pronounce proton (audio)
: 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
protonic adjective

Examples of proton in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
In the case of a passing lead atom, the loss of three protons through this process results in the formation of gold. Victoria Corless, Space.com, 13 May 2025 However, a more common result is a process called electromagnetic dissociation which can see a small number of protons stripped off a lead ion with the removal of three protons effectively turning lead with its 82 protons into gold with its 79. Tim Treadgold, Forbes.com, 13 May 2025 And a new analysis of protons trapped in the inner radiation belt that surrounds Earth suggests a new Gleissberg cycle may be beginning. Meghan Bartels, Scientific American, 9 May 2025 Elements are determined by their number of protons. Margherita Bassi, Smithsonian Magazine, 7 May 2025 See All Example Sentences for proton

Word History

Etymology

Greek prōton, neuter of prōtos first — more at proto-

First Known Use

1920, in the meaning defined above

Time Traveler
The first known use of proton was in 1920

Browse Nearby Words

Cite this Entry

“Proton.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/proton. Accessed 20 May. 2025.

Kids Definition

proton

noun
pro·​ton ˈprō-ˌtän How to pronounce proton (audio)
: 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
protonic adjective

Medical Definition

proton

noun
pro·​ton ˈprō-ˌtän How to pronounce proton (audio)
: 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
protonic adjective

More from Merriam-Webster on proton

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