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

The researchers focused on the reverse reaction because it plays a key role in the gamma process inside stars.

From Science Daily • Apr. 14, 2026

It then releases a gamma ray to reach a stable state.

From Science Daily • Apr. 14, 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

They have no compulsion to prevent one coming to harm through an extraneous agency such as gamma rays.

From "I, Robot" by Isaac Asimov