iso·​spin ˈī-sə-ˌspin How to pronounce isospin (audio)
: a quantum characteristic of a group of closely related subatomic particles (such as a proton and a neutron) handled mathematically like ordinary spin with the possible orientations in a hypothetical space specifying the number of particles of differing electric charge comprising the group

called also isotopic spin

Examples of isospin in a Sentence

Recent Examples on the Web In theory, the amplitudes should obey certain relations that apply to the Standard Model, like isospin symmetry, but — as the LHCb collaboration has concluded — measurements show our observations to be inconsistent with those expectations. Ethan Siegel, Forbes, 12 Mar. 2021

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'isospin.' 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

1961, in the meaning defined above

Time Traveler
The first known use of isospin was in 1961

Dictionary Entries Near isospin

Cite this Entry

“Isospin.” Dictionary, Merriam-Webster, Accessed 23 Apr. 2024.

More from Merriam-Webster on isospin

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!