gam·​ma | \ ˈga-mə How to pronounce gamma (audio) \

Definition of gamma

 (Entry 1 of 2)

1 : the 3rd letter of the Greek alphabet — see Alphabet Table
2 : the degree of contrast of a developed photographic image or of a video image
3 : a unit of magnetic flux density equal to one nanotesla
4 : gamma ray gamma counter



Definition of gamma (Entry 2 of 2)

1 : of, relating to, or being one of three or more closely related chemical substances
2 : third in position in the structure of an organic molecule from a particular group or atom symbol γ

Examples of gamma in a Sentence

Recent Examples on the Web: Noun On the other hand, the two NASA missions, after locating a burst with their wide-field monitors, can zoom in with narrow-field instruments to study the burst’s afterglow in gamma rays and at other wavelengths. Dennis Normile, Science | AAAS, "China launches gamma ray–hunting satellites to trace sources of gravitational waves," 10 Dec. 2020 Another 1,000 tons of the same concoction envelops the core of detector, and 2,300 tons of water surround the whole apparatus, shielding it from gamma rays and neutrons spit out by the rocks of the Gran Sasso mountain. Charlie Wood, Popular Science, "We still don’t really know what’s inside the sun—but that could change very soon," 30 Nov. 2020 In other words, perhaps gamma-ray bursts represent the rare occasions that jets escape their stars and don't slow down too much. Anna Y. Q. Ho, Scientific American, "Strange Supernovae Upend Expectations," 26 Nov. 2020 In the days before the scientists observed the FRBs, the magnetar, which is called SGR 1935+2154, had become extremely active by shooting x-ray and gamma rays out across the galaxy. Jennifer Leman, Popular Mechanics, "Mystery Radio Burst Source Finally Revealed: It's Coming From Inside the Milky Way," 6 Nov. 2020 Retail traders may often hear advanced traders mention gamma scalping, which is, very broadly speaking, adjusting an options position frequently with a primary goal of not losing money due to theta (see below). Nick Ravo, WSJ, "These Options Terms Are Greek to You," 5 Oct. 2020 Back in May, astronomers noted an overwhelming pulse in gamma rays on a variety of instruments. Jessica Boddy, Popular Science, "This ‘kilonova’ shines so bright, it defies the odds," 13 Nov. 2020 Visitors are challenged in virtual exercises to find gamma rays, calculate the engine power needed for air cargo drops, build bridges and diagnose illnesses. Washington Post, "New Army Museum highlights innovation and individual stories," 11 Nov. 2020 But on April 27, two NASA space telescopes picked up x-ray and gamma-ray bursts emanating from a magnetar in the Milky Way called SGR 1935+2154. National Geographic, "Mysterious radio signal spotted in Milky Way for first time," 4 Nov. 2020 Recent Examples on the Web: Adjective The Avengers Campus will feature the comic-favorite drink (minus the gamma blood) that's also available as a reusable soda-can novelty cup. Bryan Alexander, USA TODAY, "Marvel-inspired eats at Disney's Avengers Campus, from Shawarma Palace to Quantum Pretzel," 13 Mar. 2020 And the worldwide shortage of gamma ferric oxide has brought tape production to a crawl. David Grossman, Popular Mechanics, "We're Facing a Worldwide Cassette Shortage, So Hug Your Nearest Hipster," 11 Oct. 2019 The amount of energy being lost is so large that some of it is emitted in the form of the highest-energy category of photons, gamma-rays. John Timmer, Ars Technica, "Data from the International Space Station confirms: Lightning is insane," 10 Dec. 2019 One way to generate these specific oscillations, called gamma rhythms, is to flash a light, or play a clicking noise at the frequency. Katherine Ellen Foley, Quartz, "The future of Alzheimer’s treatment can’t bank on just one drug," 24 Oct. 2019 Some neuroscientists think that these gamma waves may not do much at all. Diana Kwon, Scientific American, "“Metronome” Neurons Act Like Timekeepers in Mouse Brains," 18 July 2019 There are neuroscientists who think that gamma rhythms, fast brain waves that fluctuate at a frequency of approximately 40 cycles per second, play this role. Diana Kwon, Scientific American, "“Metronome” Neurons Act Like Timekeepers in Mouse Brains," 18 July 2019 In addition to remaining unperturbed by the outside world, this specific subset of cells tended to spike regularly at gamma-range intervals, like a metronome. Diana Kwon, Scientific American, "“Metronome” Neurons Act Like Timekeepers in Mouse Brains," 18 July 2019 Researchers also observe an increase in gamma waves, synchronized firing by groups of neurons at a frequency implicated with conscious awareness and executive functions such as voluntary action and decision-making. Achilleas Pavlou, Quartz, "A lucid dream researcher’s tips for controlling your dreams," 29 June 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'gamma.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of gamma


15th century, in the meaning defined at sense 1


1834, in the meaning defined at sense 1

History and Etymology for gamma


Middle English, borrowed from Latin, borrowed from Greek gȧmma, borrowed from Phoenician *gaml-, perhaps with the original sense "throwing stick"


attributive use of gamma entry 1

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Time Traveler for gamma

Time Traveler

The first known use of gamma was in the 15th century

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Statistics for gamma

Last Updated

15 Dec 2020

Cite this Entry

“Gamma.” Dictionary, Merriam-Webster, Accessed 17 Jan. 2021.

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How to pronounce gamma (audio)

English Language Learners Definition of gamma

: the third letter of the Greek alphabet


gam·​ma | \ ˈgam-ə How to pronounce gamma (audio) \

Medical Definition of gamma

 (Entry 1 of 2)

1 : the third letter of the Greek alphabet symbol Γ or γ
2 : a unit of magnetic flux density equal to one nanotesla
3 : gamma ray usually used as the attributive form of gamma ray gamma counter


variants: or γ-

Medical Definition of gamma (Entry 2 of 2)

1 : of or relating to one of three or more closely related chemical substances the gamma chain of hemoglobin γ-yohimbine used somewhat arbitrarily to specify ordinal relationship or a particular physical form and especially one that is allotropic, isomeric, or stereoisomeric (as in gamma benzene hexachloride)
2 : third in position in the structure of an organic molecule from a particular group or atom also : occurring at or having a structure characterized by such a position γ-hydroxy acids
3 of streptococci : producing no hemolysis on blood agar plates

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