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

Baryon number can be conserved even when individual protons and neutrons transform into other baryons; what remains unchanged is the total baryon number. — Rupendra Brahambhatt, Interesting Engineering, 16 Aug. 2026

Most potassium atoms are a stable form known as potassium-39, containing 19 protons and 20 neutrons. — Encyclopedia Britannica, 14 Aug. 2026

The versions of these elements used in the study have the same total number of protons and neutrons combined, but ruthenium has four more protons and four fewer neutrons, making its nucleus more electrically charged. — Joseph Howlett, Scientific American, 13 Aug. 2026

Solar storms, like the one in August 1972 that hit during the gap between the Apollo 16 and Apollo 17 missions, throw bursts of protons intense enough to raise an astronaut’s cancer risk or even cause radiation sickness. — Jacek Krywko, ArsTechnica, 13 Aug. 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