rest mass


: the mass of a body exclusive of additional mass the body acquires by its motion according to the theory of relativity

Examples of rest mass in a Sentence

Recent Examples on the Web All these experiments measure energy, but that's pretty much the same as the rest mass of the particle. Phil Plait, Discover Magazine, 13 Dec. 2011 When the temperature of the Universe drops below a certain, critical threshold — a threshold set by the rest mass of each particle — fewer and fewer collisions occur that have enough energy to allow for creation to be a possibility. Ethan Siegel, Forbes, 2 Sep. 2021 While rest mass energy, gravitational potential energy, and kinetic energy are all concepts that work perfectly well with Newtonian mechanics and gravitation, the idea of gravitation radiation is inherently novel in Einstein’s General Relativity. Ethan Siegel, Forbes, 5 May 2021 The Higgs symmetry was restored early on, and so none of the Standard Model particles possessed a rest mass prior to that time. Ethan Siegel, Forbes, 21 Apr. 2021

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'rest mass.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1914, in the meaning defined above

Time Traveler
The first known use of rest mass was in 1914

Dictionary Entries Near rest mass

Cite this Entry

“Rest mass.” Dictionary, Merriam-Webster, Accessed 21 Feb. 2024.

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