beta
noun
the second letter of the Greek alphabet (β, B).
beta
American
[bey-tuh, bee-]
/ ˈbeɪ tə, ˈbi- /
noun
betas
plural
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the second letter of the Greek alphabet (β, B).
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the consonant sound represented by the second letter of the Greek alphabet.
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Astronomy. Beta, a star that is usually the second brightest of a constellation.
The second brightest star in Taurus is Beta Tauri.
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Chemistry.
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one of the possible positions of an atom or group in a compound.
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one of two or more isomeric compounds.
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the second of any series, as in chemistry or physics.
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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.
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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.
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Trademark. Beta, a brand of tape format for VCR tape, incompatible with other formats.
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Chiefly British. a grade showing that a student is in the middle or second of three scholastic sections in a class.
adjective
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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.
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(of an animal) having the second-highest rank in a dominance hierarchy.
the beta female in a pack of meerkats.
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Slang: Sometimes Disparaging. being or relating to a man who is perceived to be weak, mild-mannered, and unimpressive.
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beta
1
British
/ ˈbiːtə /
noun
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the second letter in the Greek alphabet (Β, β), a consonant, transliterated as b
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the second highest grade or mark, as in an examination
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(modifier)
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involving or relating to electrons
beta emitter
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relating to one of two or more allotropes or crystal structures of a solid
beta iron
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relating to one of two or more isomeric forms of a chemical compound
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Beta
2
British
/ ˈbiːtə /
noun
Other Word Forms
Noun Inflected Forms
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
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
He also courted strong and straight — and unavailable — alpha men to whom he appeared happy to play the beta role of political ingénue.
From Salon ● Jul. 13, 2026
Amyloid beta places additional stress on nerve cells, which leads to the formation of even more inactive GRK2.
From Science Daily ● Jun. 8, 2026
A beta version of Siri AI will be available later this year to supported devices set to English -- although not in the EU.
From BBC ● Jun. 8, 2026
Pluvicto carries a beta particle that travels for a longer range but is less lethal, while the new therapy uses an alpha particle that is more lethal but travels shorter distances, the analyst says.
From The Wall Street Journal ● Jun. 2, 2026
Too much beta carotene turns you orange, too much calcium gives you kidney stones.
From "Cat's Eye" by Margaret Atwood
This Beta 3D experience is all powered by live official Fifa data and technology from XR company Immersiv.io.
From BBC ● Jun. 23, 2026
Since the bottom of that brief selloff through Tuesday, the S&P 500 High Beta Index has beaten a group of low-volatility stocks by a whopping 123 percentage points.
From The Wall Street Journal ● Jun. 3, 2026
Beta blockers became standard after heart attacks at a time when modern cardiac care looked very different.
From Science Daily ● May 25, 2026
Spark will start rolling out to testers on Tuesday, with the Beta expected to go out to Google AI Ultra subscribers in the U.S. next week.
From Barron's ● May 19, 2026
The optical sensors seem to have mistaken Alpha and Beta Centauri for Canopus.
From "Cosmos" by Carl Sagan
The screen includes stocks with betas that range from just as 0.01% to -1.68%.
From Barron's ● Jun. 24, 2026
Consider the performance of a hypothetical portfolio that buys the 10% of stocks with the highest betas and sells short the decile of stocks with the lowest betas.
From MarketWatch ● Oct. 23, 2025
“We’re betas pretending to be alphas,” Denton said.
From New York Times ● Nov. 3, 2022
If you missed out on those betas, you can at least get some idea of what the game will look like by watching some Overwatch League.
From The Verge ● Aug. 16, 2022
Greek letters move across the undersides of his eyelids: isosceles triangles, betas, sine curves.
From "All the Light We Cannot See" by Anthony Doerr
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
