noun Physics, Chemistry.

a positively charged elementary particle that is a fundamental constituent of all atomic nuclei. It is the lightest and most stable baryon, having a charge equal in magnitude to that of the electron, a spin of ½, and a mass of 1.673 × 10−27 kg. Symbol: P

Nearby words

  1. protolanguage,
  2. protolithic,
  3. protolog,
  4. protomartyr,
  5. protomorphic,
  6. proton microscope,
  7. proton number,
  8. proton synchrotron,
  9. proton-proton chain,
  10. proton-pump inhibitor

Origin of proton

1915–20; noun use of Greek prôton, neuter of prôtos first

Related formspro·ton·ic, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for protonic

  • Arcot threw out his protonic shield, and retreated to half a million miles, as he had said.

    Invaders from the Infinite|John Wood Campbell
  • Then it was over, and the skies were clear once more as Arcot lowered the protonic screen silently.

    Invaders from the Infinite|John Wood Campbell
  • And the six smaller machines, which Arcot had succeeded in interconnecting with the protonic generator, were whining too.

    Invaders from the Infinite|John Wood Campbell

British Dictionary definitions for protonic



chem (of a solvent, such as water) able to donate hydrogen ions to solute molecules



a stable, positively charged elementary particle, found in atomic nuclei in numbers equal to the atomic number of the element. It is a baryon with a charge of 1.602176462 × 10 –19 coulomb, a rest mass of 1.672 62159 × 10 –27 kilogram, and spin 1/2

Word Origin for proton

C20: from Greek prōtos first

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for protonic



1920 in physics, coined by English physicist Ernest Rutherford (1871-1937) from noun use of Greek proton, neuter of protos "first" (see proto-), on analogy of electron; supposedly because hydrogen was hypothesized as a constituent of all the elements. The word was used earlier in embryology (1893) as a translation of German anlage ("fundamental thing") based on Aristotle's phrase he prote ousia to proton.

Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for protonic




A stable, positively charged subatomic particle in the baryon family having a mass 1,836 times that of the electron.

The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for protonic



A stable subatomic particle in the baryon family having a mass of 1.672 X 10-24 grams (1,836 times that of the electron) and a positive electric charge of approximately 1.602 X 10-19 coulombs. Protons make up part of the nucleus of all atoms except hydrogen, whose nucleus consists of a single proton. In neutral atoms, the number of protons is the same as the number of electrons. In positively charged atoms, the number of protons is greater than the number of electrons, and in negatively charged atoms electrons outnumber protons. Protons are believed to be composed of two up quarks and one down quark. See Table at subatomic particle.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Culture definitions for protonic



An elementary particle with a positive charge, found in the nucleus of an atom.


A proton is over a thousand times heavier than an electron.


Protons and neutrons make up most of an atom's mass.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.