Jump To:

• gamma
  gamma

  noun

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

  noun

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

gamma

American  

[gam-uh] / ˈgæm ə /

noun

gammas plural

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.

---

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

---

Gamma ² British  

/ ˈɡæmə /

noun

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

   Gamma Leonis

---

Other Word Forms

Noun Inflected Forms

• gammas
  plural

Etymology

Origin of gamma

From the Greek word gámma

Example Sentences

See Examples For:

gamma Gamma gammas

That distance was too great for the instrument to detect gamma rays coming from the planet, but scientists believed it might still register neutrons escaping from the Martian surface and atmosphere.

From Science Daily ● Jul. 28, 2026

Eradication was possible through the sterile insect technique, which uses gamma radiation to irradiate screwworm pupae and create sterile male flies.

From Los Angeles Times ● Jun. 6, 2026

Electrons and positrons can collide and transform into gamma-ray photons, while gamma rays themselves can collide and create new particles.

From Science Daily ● May 27, 2026

“You have a massive gamma squeeze going on right now in Micron,” said Michael Kramer of Mott Capital Management.

From MarketWatch ● May 26, 2026

The next question came in a friendly, offhand manner, “Ever work with gamma rays?”

From "I, Robot" by Isaac Asimov

This past week, the Squeeze Metrics Gamma Index, which measures the dollar value of option dealers’ exposure to the call options they have sold to clients, hit its highest level since 2021.

From MarketWatch ● May 17, 2026

Gamma is essentially the rate of change in a stock option’s delta, and the delta is how an option price changes with changes in the underlying stock.

From Barron's ● Apr. 10, 2026

Jackson sat with both Jewish and Black employees at Gamma before signing Ye, according to people familiar with the matter.

From The Wall Street Journal ● Jan. 28, 2026

"Gamma rays, and specifically the excess light we're observing at the center of our galaxy, could be our first clue."

From Science Daily ● Oct. 18, 2025

Or is this just how they are here at Gamma Alpha Psi?

From "Ask the Passengers" by A.S. King

To improve on the experiment, I need to beat down the accidental rate—in particular, the rate caused by gammas traveling straight from the sodium to the Geiger counter rather than scattering off the aluminum.

From Scientific American ● Feb. 14, 2013

A couple of hundred gammas per minute leak out through each hole, forming a pair of gamma-ray beams.

From Scientific American ● Feb. 14, 2013

Just because the gammas emerge in pairs doesn’t mean they are entangled, though.

From Scientific American ● Feb. 14, 2013

A magnetometer on the side where the nuclear device was detonated quickly registered an increase of nine gammas* in the local magnetic field.

From Time Magazine Archive

Swiftly the beams went through the range of radiation, through radio and short radio, infra-red, visible light, ultra-violet, X-ray, the gammas and the cosmics—a terrific flood of billions of horsepower.

From Empire by Simak, Clifford D.