gamma

UK: /ˈgæmə/ US: /ˈgæmə/ ,(gam′ə)

WordReference Random House Learner's Dictionary of American English © 2025

gam•ma /ˈgæmə/   n. [countable] , pl. -mas. 

1. the third letter of the Greek alphabet (&Ggr;, γ).

WordReference Random House Unabridged Dictionary of American English © 2025

gam•ma  (gam′ə), n. 

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. (cap.) [Astron.] 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. [Photog.] 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 Brit.] a grade showing that an individual student is in the third, or lowest, of three scholastic sections in a class. Cf. alpha (def. 7), beta (def. 8).

• Greek gámma

Collins Concise English Dictionary © HarperCollins Publishers::

gamma / 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. 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) involving or relating to photons of very high energy: a gamma detector
6. relating to one of two or more allotropes or crystal structures of a solid: gamma iron
7. 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

Etymology: 14th Century: from Greek; related to Hebrew gīmel third letter of the Hebrew alphabet (probably: camel)