beta

American  

[bey-tuh, bee-] / ˈbeɪ tə, ˈbi- /

noun

1. the second letter of the Greek alphabet (β, B).

2. the consonant sound represented by the second letter of the Greek alphabet.

3. Astronomy. Beta, a star that is usually the second brightest of a constellation.

   The second brightest star in Taurus is Beta Tauri.

4. Chemistry.

   1. one of the possible positions of an atom or group in a compound.

   2. one of two or more isomeric compounds.

5. the second of any series, as in chemistry or physics.

6. Computers. the phase of hardware or software development in which a product is tested in the environment for which it was designed.

   Our newest product, currently in beta with new features being added regularly, is perfect for busy professionals who need to organize their calendars.

7. Also called beta coefficient.  Also called beta line.  Stock Exchange. an arbitrary measure of the volatility of a given stock using an index of the volatility of the market as a whole.

   A beta of 1.1 indicates a stock that is 10 percent more volatile than the market.

8. Trademark. Beta, a brand of tape format for VCR tape, incompatible with other formats.

9. Chiefly British. a grade showing that a student is in the middle or second of three scholastic sections in a class.

10. beta male.

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adjective

1. Computers. being, relating to, or undergoing the phase of product development in which a product is tested in the environment for which it was designed.

   The beta version of the new game, featuring a four-player mode, will be unveiled next month.

2. 1. (of an animal) having the second-highest rank in a dominance hierarchy.

      the beta female in a pack of meerkats.

   2. Slang: Sometimes Disparaging. being or relating to a man who is perceived to be weak, mild-mannered, and unimpressive.

beta ¹ British  

/ ˈbiːtə /

noun

1. the second letter in the Greek alphabet (Β, β), a consonant, transliterated as b

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

3. (modifier)

   1. involving or relating to electrons

      beta emitter

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

      beta iron

   3. relating to one of two or more isomeric forms of a chemical compound

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Beta ² British  

/ ˈbiːtə /

noun

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

   Beta Persei

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Etymology

Origin of beta

First recorded in 1350–1400; from Latin, from Greek bêta, from Phoenician bt “house,” also the name of the second letter of the Phoenician alphabet; cf. beth

Explanation

Beta is the second letter of the Greek alphabet. It also refers to a preliminary model of software or hardware that's being tested but is not quite a finished product. The Greek letter beta, β, is used in several fields, including statistics, physics, finance, and geometry, to represent different things. Because it's the second letter in the Greek alphabet, right after alpha, it's often used to mean "secondary" or "second in order" — as in a "beta particle," the second type of radiation discovered by Ernest Rutherford. In technology, a beta version of software is in the secondary testing phase, when it's a nearly complete prototype. A company may let some people use the beta version to help work out some kinks before releasing the final version.

Example Sentences

Although the service isn’t public yet, information has been slowly rolled out through beta users, or those helping test the product.

From MarketWatch • Apr. 16, 2026

The drugs attack a sticky gunk – called beta amyloid – that builds up in the spaces between brain cells in Alzheimer's disease.

From BBC • Apr. 16, 2026

We also looked for stocks that had at least kept pace with the stock market’s 0.6% year-to-date return and that boast a beta of less than 1.

From Barron's • Apr. 14, 2026

HappyHorse “is currently under internal beta test and we are expecting to launch API access for the model in the near future,” said a spokesperson at Token Hub, Alibaba’s newly created AI-focused unit.

From The Wall Street Journal • Apr. 10, 2026

So I went down and spoke to Doerr and Jim Clark, and I began using the beta version of the Mosaic browser.

From "The World Is Flat" by Thomas L. Friedman