gamma

American  

[gam-uh] / ˈgæm ə /

noun

1. the third letter of the Greek alphabet (Γ, γ).

2. the consonant sound represented by this letter.

3. the third in a series of items.

4. Astronomy. Gamma, a star that is usually the third brightest of a constellation.

   The third brightest star in the Southern Cross is Gamma Crucis.

5. a unit of weight equal to one microgram.

6. Physics. a unit of magnetic field strength, equal to 10− 5 gauss.

7. Photography. a measure of the degree of development of a negative or print.

8. Television. an analogous numerical indication of the degree of contrast between light and dark in the reproduction of an image in television.

9. Chiefly British. a grade showing that an individual student is in the third, or lowest, of three scholastic sections in a class.

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gamma ¹ British  

/ ˈɡæmə /

noun

1. the third letter in the Greek alphabet (Γ, γ), a consonant, transliterated as g. When double, it is transcribed and pronounced as ng

2. the third highest grade or mark, as in an examination

3. a unit of magnetic field strength equal to 10 ^–5 oersted. 1 gamma is equivalent to 0.795 775 × 10 ^–3 ampere per metre

4. photog television the numerical value of the slope of the characteristic curve of a photographic emulsion or television camera; a measure of the contrast reproduced in a photographic or television image

5. (modifier)

   1. involving or relating to photons of very high energy

      a gamma detector

   2. relating to one of two or more allotropes or crystal structures of a solid

      gamma iron

   3. relating to one of two or more isomeric forms of a chemical compound, esp one in which a group is attached to the carbon atom next but one to the atom to which the principal group is attached

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Gamma ² British  

/ ˈɡæmə /

noun

1. (foll by the genitive case of a specified constellation) the third brightest star in a constellation

   Gamma Leonis

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Etymology

Origin of gamma

From the Greek word gámma

Example Sentences

One of the biggest remaining uncertainties has been how often selenium-74 is broken apart by gamma rays during stellar explosions.

From Science Daily • Apr. 14, 2026

One leading explanation for the creation of p-nuclei is the gamma process, which takes place in certain types of supernova explosions.

From Science Daily • Apr. 14, 2026

Still, other explanations are possible, including gamma rays produced by astrophysical sources like pulsars.

From Science Daily • Apr. 10, 2026

“A lot of the reason for the volatility is the hedging of this short gamma position, which is very near the money right now,” Roos said.

From MarketWatch • Mar. 28, 2026

In fact bursts of gamma rays from space have been detected by satellites originally constructed to look for violations of the Test Ban Treaty.

From "A Brief History of Time: And Other Essays" by Stephen Hawking