proton

noun

pro·​ton ˈprō-ˌtän 

: 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

prō-ˈtä-nik 

adjective

Examples of proton in a Sentence

Recent Examples on the Web

Isotopes are atoms of the same element that have the same number of protons but differing numbers of neutrons. —Keith Cooper, Space.com, 30 Mar. 2026

But there are fewer than 50 proton therapy centers in the United States. —Caleb Hellerman, CNN Money, 29 Mar. 2026

On Tuesday the physicists loaded 92 antiprotons—the antimatter version of protons—into a truck and drove them around for about an hour and a half. —Emma Gometz, Scientific American, 25 Mar. 2026

Deuterium, a stable and non-radioactive isotope of hydrogen that features a neutron in addition to the single proton in its core, is extremely abundant across the universe. —Victor Tangermann, Futurism, 25 Mar. 2026

Word History

Etymology

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

First Known Use

1920, in the meaning defined above

Phrases Containing proton

• proton pump inhibitor
• proton synchrotron

Rhymes for proton

• anton
• argon
• axon
• baronne
• baryon
• baton
• boron
• buisson
• bygone
• capon
• cardon
• chiffon

Kids 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

protonic

prō-ˈtän-ik 

adjective

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

protonic

prō-ˈtän-ik 

adjective