be·​ta | \ ˈbā-tə How to pronounce beta (audio) , chiefly British ˈbē-\

Definition of beta

 (Entry 1 of 2)

1 : the 2nd letter of the Greek alphabet — see Alphabet Table
3 : a measure of the risk potential of a stock or an investment portfolio expressed as a ratio of the stock's or portfolio's volatility to the volatility of the market as a whole
4 : a nearly complete prototype of a product (such as software) the beta version also : a stage of development in which a product is nearly complete but not yet ready for release released in beta



Definition of beta (Entry 2 of 2)

: second in position in the structure of an organic molecule from a particular group or atom beta substitution often used in combination symbol β

Examples of beta in a Sentence


a program that is currently in beta

Recent Examples on the Web: Noun

The website, now in beta testing, was developed to help entrepreneurs and small business owners find their way to assistance through local resources. William Thornton |,, "Entrepreneurial tool Bham BizHub now available," 10 July 2019 With today's surprise launch, the game is now available in the U.S. and U.K. The game has also been in beta testing in both New Zealand and Australia for about a month. Thom Craver, CBS News, "Harry Potter augmented reality game arrives a day early," 20 June 2019 Apple has indicated Sign In with Apple will become available for beta testing this summer. Lauren Goode, WIRED, "App Makers Are Mixed on ‘Sign In With Apple’," 15 June 2019 Members who sent comments to potential matches during beta testing had a 25 percent higher chance of getting liked back, the company says. Ashley Carman, The Verge, "Coffee Meets Bagel redesigns its app and introduces profile commenting," 11 Dec. 2018 There are also more food options, like a bagel, which after beta testing, now includes some cream cheese smear (Thank god. Carolyn Twersky, Seventeen, "Check Out the Newest Wave of Emojis That You Can Get on Your Phone Now," 31 Oct. 2018 In 2016, the company began beta testing WeLive — essentially WeWork for residential tenants. Gaby Del Valle, Vox, "WeWork is tracking how much its members drink during the workday," 31 Oct. 2018 Wargaming is planning extensive beta testing of the features. Gordon Mah Ung, PCWorld, "World of Warships dives deep for new players, adding submarines to popular naval combat game," 18 Sep. 2018 Getting to the point of beta testing Stanley’s interactive interview has been months in the making, Hays said. Michelle Chavez, Fox News, "Future generations can speak to Holocaust survivors – via hologram technology," 25 July 2018

Recent Examples on the Web: Adjective

With about 80 calories per large peach, this fruit provides a handful of nutrients including vitamin C, beta carotene and potassium. Darlene Zimmerman, Detroit Free Press, "Peach-glazed chicken: Easy, one-skillet recipe is done in 30 minutes," 7 July 2019 Apple Apple has opened up its beta testing program today (June 24) to anyone wishing to test out the latest software for the iPhone, iPad, and Mac computers. Mike Murphy, Quartz, "You can try out iOS 13 now—if you dare," 24 June 2019 The PlayStation version, however, will include early beta access and unique benefits that will be revealed at a future date. Nick Romano,, "Marvel's Avengers videogame revealed: Watch the trailer," 11 June 2019 Microsoft has restarted the Windows 10 October 2018 Update to members of its Windows Insider beta team. Mark Hachman, PCWorld, "Microsoft restarts Windows 10 October 2018 Update, blaming data loss on misdirected folders," 9 Oct. 2018 More evidence of the stand, which is supposed to be a wireless charger that docks your phone in portrait mode, was found by 9to5Google today hidden within a beta version of the Google app. Dami Lee, The Verge, "Animation reveals possible Google Pixel wireless charging stand," 21 Sep. 2018 PROTOTYPES Beer and beta testing Visit the Wayfair office for an evening of beta testing beer prototypes provided by beverage delivery app Drizly. Margeaux Sippell,, "Business agenda," 26 June 2018 But there are also wine betas like my friend Peggy, who are knowledgeable but prefer the beta role. Lettie Teague, WSJ, "Are You a Wine Alpha or a Wine Beta?," 8 June 2018 This is expressed in a number of ways, most clearly through the existence of more distinct communities of species among the sacred groves than in the control sites (this phenomenon is known as beta diversity). John Healey, John Halley And Kalliopi Stara, Smithsonian, "Sacred Sites Can Also Be Hotspots of Conservation," 17 May 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'beta.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of beta


14th century, in the meaning defined at sense 1


1862, in the meaning defined above

History and Etymology for beta


Middle English betha, from Latin beta, from Greek bēta, of Semitic origin; akin to Hebrew bēth beth

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Statistics for beta

Last Updated

15 Jul 2019

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Time Traveler for beta

The first known use of beta was in the 14th century

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More Definitions for beta



Financial Definition of beta

What It Is

Beta is a measure of a stock's volatility relative to the overall market. It is most often calculated using a stock's movements relative to the S&P 500 Index over the trailing 12-month period.

How It Works

A stock's beta is determined by analyzing how much its return fluctuates in relation to the overall market return. A stock with a beta of 1.0 will tend to move higher and lower in lockstep with the overall market. Stocks with a beta greater than 1.0 tend to be more volatile than the market, and those with betas below 1.0 tend to be less volatile than the underlying index. Stocks with betas of zero generally move independently of the broader market. And finally, stocks with negative betas tend to move in the opposite direction relative to the broader market. When the S&P tumbles, stocks with negative betas will move higher, and vice versa.

For example, a stock with a beta of 2.0 is usually twice as volatile as the broader market. If the S&P 500 were to fall by -10% next year, then the stock would be expected to fall about -20% (assuming that the stock behaves similar to how it has in the past). The stock would also be expected to gain more in an up market.

Beta is a measure of systematic risk.

Why It Matters

The definition of beta on InvestingAnswersBeta can help investors choose investments that match their specific risk preferences. A risk-averse investor, for example, may want to avoid overweighting their portfolio with high-beta stocks to avoid excessive volatility.

Individual stock betas are extremely important when putting together a portfolio of assets. A diversified portfolio consisting of assets with different betas lowers the overall risk of the portfolio.

Investors should note that beta is calculated using past price fluctuations and does not ensure that a security will behave the same going forward. Beta is used (most frequently in the Capital Asset Pricing Model, or CAPM) to forecast expected return of a stock or portfolio, not the actual return.

Source: Investing Answers



English Language Learners Definition of beta

: the second letter of the Greek alphabet
: a version of a product (such as a computer program) that is almost finished and that is used for testing


be·​ta | \ ˈbāt-ə, chiefly British ˈbē-tə\

Medical Definition of beta

 (Entry 1 of 2)

1 : the second letter of the Greek alphabet symbol Β or β
3 : beta wave


variants: or β-

Medical Definition of beta (Entry 2 of 2)

1 : of or relating to one of two or more closely related chemical substances the beta chain of hemoglobin β-yohimbine used somewhat arbitrarily to specify ordinal relationship or a particular physical form and especially one that is allotropic, isomeric, stereoisomeric, or sometimes polymeric (as in β-D-glucose)
2 : second in position in the structure of an organic molecule from a particular group or atom also : occurring at or having a structure characterized by such a position beta substitution
3 : producing a zone of decolorization when grown on blood media used of some hemolytic streptococci or of the hemolysis they cause

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More from Merriam-Webster on beta

Rhyming Dictionary: Words that rhyme with beta

Spanish Central: Translation of beta

Nglish: Translation of beta for Spanish Speakers

Britannica English: Translation of beta for Arabic Speakers Encyclopedia article about beta

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