Definition of proton in English:

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Pronunciation: /ˈprōˌtän/


A stable subatomic particle occurring in all atomic nuclei, with a positive electric charge equal in magnitude to that of an electron, but of opposite sign.

The mass of the proton is 1,836 times greater than that of the electron. The atoms of each chemical element have a characteristic number of protons in the nucleus; this is known as the atomic number. The common isotope of hydrogen has a nucleus consisting of a single proton.

Example sentences
  • Overall, atoms are neutral and the number of protons in their nuclei equals the number of electrons.
  • The matter was composed primarily of an ionized gas of electrons, protons, and helium nuclei.
  • An alpha particle consists of two protons and two neutrons; it is the nucleus of a helium atom.



Pronunciation: /prōˈtänik/
Example sentences
  • The organic purity of the organoarsenic species was determined by protonic nuclear magnetic resonance.
  • The rate of the former, productive reaction is determined by the protonic conductance of the consumer.
  • It consists of an interdependence between the electronic and protonic captures, which results from electrostatic interactions between redox and protonatable groups.


1920s: from Greek, neuter of prōtos 'first'.

Words that rhyme with proton


For editors and proofreaders

Syllabification: pro·ton

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