meson

Etymology

It is formed from English meso- + -on,^[2][3][4][5] from Ancient Greek μέσος (mésos, “middle”),^[6] from Proto-Indo-European *médʰyos (“middle”),^[6] because the particles were intermediate in mass between electrons and protons.^[6][2] It replaced mesotron (1938), formed with -tron as in electron.^[2][7][6] Barnhart explains the change by the influence of the suffix in proton, and perhaps of an earlier French méson, about 1935;^[7] Wiktionary credits the coinage to Homi Bhabha in 1939.^[1]

Earliest recorded meaning

A subatomic particle intermediate in mass between the electron and the proton, first found in cosmic rays: 1939, in a letter by H. J. Bhabha to Nature.^[2][4][7]

Semantic evolution

The OED's notes on mesotron tell the background: in 1935 Hideki Yukawa proposed a particle carrying the force between nucleons; the mesotron found in 1936 had some of its properties but not all, and only the pi-meson, or pion, found in 1947, met all of them.^[2] The particle first called a mesotron is now the muon, which is no longer counted a meson.^[8][2] The definition has accordingly moved from mass to structure: dictionaries now define a meson as a particle made of a quark and an antiquark, with zero or whole-number spin, that takes part in the strong interaction.^[3][9][2] The 1989 edition of the OED records meson factory, an accelerator producing intense beams of mesons, from 1966.^[10]

Timeline

• 1939 – a particle intermediate in mass between an electron and a proton.^[2][4][7]
• 1966 – meson factory, an accelerator producing intense meson beams.^[10]

Meanings

Noun

1. (physics) Any of a family of subatomic particles, such as the pion and kaon, made of a quark and an antiquark, with zero or integral spin, that take part in the strong interaction.^[3][4][8][9]
2. (physics) Originally, any particle with a mass between those of the electron and the proton.^[2][9][4]

Word family

• mesonic
• K-meson
• mesic
• eta meson
• pi meson
• B meson

Related words

• mesotron
• meso-
• -on
• muon
• pion

Usage notes

Two other words of this spelling are recorded.^[2][9] Meson, an inn or boarding house in Spain, Mexico and the American Southwest (from 1817), is from Spanish mesón (“inn”), ultimately from Latin mansiō, the source of mansion.^[2][9] Meson in anatomy, the median plane dividing the body into two symmetrical halves (from 1881), is from Ancient Greek μέσον (méson, “midst”), the neuter of the adjective.^{[2][9][6][11]}

References

1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k l Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
4. ^ a b c d e Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
5. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
6. ^ a b c d e Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
7. ^ a b c d Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
8. ^ a b Collins English Dictionary (2023), Glasgow: HarperCollins
9. ^ a b c d e f Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
10. ^ a b Simpson, J. A.; Weiner, E. S. C., eds. (1989), The Oxford English Dictionary, 2nd ed., Oxford: Clarendon Press
11. ^ Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.