gamma

Etymology

It is borrowed from Latin gamma,^[2][3][4] the Latin name of the third letter of the Greek alphabet, and its source Ancient Greek γάμμα (gámma).^[2][5][3][6] The Greek name comes from a Semitic form, with assimilation of the consonants:^[2] the OED compares Biblical Hebrew גימל (gīmel),^[2][3][4][1] the name of the third Hebrew letter, the source of gimel.^[1] Etymonline and Barnhart give the meaning of the letter name as "camel", Barnhart saying that the letter grew out of a hieroglyph of a camel,^[5][3] but the OED calls the further etymology and the reason for the name uncertain and disputed,^[2] and Wiktionary traces it to a Semitic word for a weapon, perhaps a sling or a throwing stick.^[1] In Latin the letter also stood for the numeral three, and in medieval Latin for the lowest note of the musical scale.^[2]

Earliest recorded meaning

The name of the third letter of the Greek alphabet (Γ, γ): probably before 1425, in Mandeville's Travels.^[2][3] Etymonline dates it to about 1400.^[5]

Semantic evolution

Because the letter was the third, gamma came to mark the third of a series: from 1717 the third star of a constellation, typically the third brightest, named with the genitive of the constellation's Latin name,^[2][7] from 1834 the third of a set of related chemical compounds,^[2][4] and since 1898, in Max Beerbohm first, a third-class mark in an examination.^[2] The medieval Latin use for the lowest note of the scale gave the obsolete English sense "gamut" (1602–1825).^[2][8] Other senses come from the letter's shape: the gamma moth (1799), named for the Y-shaped silver markings on its forewings, and a gamma-shaped surgical instrument (1809–48).^[2][9] Gamma rays (1903) were at first thought to be a third kind of radiation given off by radium, after alpha and beta rays, and were later found to be very short X-rays;^[5][3] the noun alone has meant a gamma ray or gamma radiation since 1919.^[2] The same year, 1903, gave the photographic sense, a measure of the contrast of an emulsion, and a unit of magnetic field strength,^[2] while since 1931 gamma was also a millionth of a gram.^[2] In Aldous Huxley's Brave New World (1932) the Gammas are a caste of low intelligence, and the word has since been used for such a person.^[2] Gamma globulin (1937) is one of three serum globulins of the blood, named alpha, beta and gamma.^[3]

Timeline

• ?a1425 – the third letter of the Greek alphabet.^[2][3]
• 1602 – in music, the gamut (obsolete after 1825).^[2]
• 1717 – the third star of a constellation.^[2]
• 1799 – the gamma moth.^[2]
• 1834 – adjective, in chemistry, the third of a set of related compounds.^[2][4]
• 1898 – a third-class mark in an examination.^[2]
• 1903 – gamma ray; a measure of photographic contrast; a unit of magnetic field strength.^[5][3][2]
• 1919 – a gamma ray, gamma radiation.^[2]
• 1931 – a microgram.^[2]
• 1932 – in Huxley's Brave New World, a member of a lower caste.^[2]
• 1937 – gamma globulin.^[3]

Modern meaning

Noun

1. The third letter of the Greek alphabet (Γ, γ), transliterated as g.
2. (astronomy) The third brightest star of a constellation, followed by the genitive of its Latin name.
3. The third grade or mark in an examination.
4. (physics) A gamma ray, or gamma radiation.
5. (photography) A measure of the contrast of a developed image or of an emulsion.
6. (physics) A unit of magnetic field strength equal to 10⁻⁵ oersted.
7. (historical) A microgram.

Adjective

1. (chemistry) Denoting the third of three or more related compounds or forms, or the third position in a molecule.

Word family

• digamma
• gammopathy
• gamma-aminobutyric acid
• gamma camera
• gamma decay
• gamma globulin
• gamma iron

Related words

• gimel
• gamut

References

1. ^ a b c d Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e f g h i j Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
4. ^ a b c d Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
5. ^ a b c d e Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
6. ^ Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
7. ^ Collins English Dictionary (2023), Glasgow: HarperCollins
8. ^ Partridge, Eric (1966), Origins: A Short Etymological Dictionary of Modern English, 4th ed., London: Routledge & Kegan Paul
9. ^ Weekley, Ernest (1921), An Etymological Dictionary of Modern English, London: John Murray