beta
noun
the second letter of the Greek alphabet (β, B).
beta
American
[bey-tuh, bee-]
/ ˈbeɪ tə, ˈbi- /
noun
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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:
The startup began testing Instinct in private beta in February and quickly generated substantial interest among venture capitalists, who are among its earliest users.
From The Wall Street Journal ● Aug. 26, 2026
“Beneath the Mist,” another action-adventure game, is also undergoing beta testing.
From The Wall Street Journal ● Aug. 21, 2026
Actresses Rachel Sennott and Kristen Bell are among the celebrities who have spoken publicly about taking beta blockers, along with the influencer Khloé Kardashian.
From BBC ● Aug. 18, 2026
Amyloid beta places additional stress on nerve cells, and that stress encourages the formation of more inactive GRK2 and more GRK2 aggregates.
From Science Daily ● Aug. 17, 2026
Eventually alpha rays were identified as helium atoms stripped of their electrons—that is, helium nuclei-—and beta rays as energetic electrons.
From "Big Science" by Michael Hiltzik
Vermont-based Beta Technologies is also competing in the race to deploy air taxis at a commercial scale.
From Los Angeles Times ● Aug. 10, 2026
Startups including Archer, Beta Technologies and Joby Aviation are vying to be the first company to successfully bring flying taxis to the masses.
From The Wall Street Journal ● Aug. 10, 2026
July saw the worst monthly performance for the Goldman Sachs High Beta Momentum Basket since November 2000, according to data from Bloomberg.
From MarketWatch ● Jul. 31, 2026
Barrientos is known for his work with the YouTube collective Beta Squad, and has appeared in the celebrity version of Bake Off on Channel 4 and presented BBC Three shows.
From BBC ● Jul. 31, 2026
The optical sensors seem to have mistaken Alpha and Beta Centauri for Canopus.
From "Cosmos" by Carl Sagan
While most of those chip makers have “betas” greater than 1—meaning their daily moves in the last few years have been larger than the S&P 500’s moves—all of the stocks above have betas below 1.
From Barron's ● Jun. 16, 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
Even in the early betas, iOS 16 was more stable than most new software, which says something not only about Apple’s capabilities but also about how much it’s really writing from scratch here.
From The Verge ● Sep. 12, 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.
