be·ta | \ˈbā-tə, 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

And The Verge reports that the same feature made its way into a beta version of Microsoft Edge for Android that rolled out to testers over the weekend. David Meyer, Fortune, "Microsoft's Mobile Browsers Join the Battle Against Annoying Ads," 25 June 2018 Since the beta version was released, private label brands have been top sellers. Ryan Suppe, ajc, "Amazon Prime members can now try on clothes before paying for them," 21 June 2018 The new security feature, which has already been tested on beta versions of iOS, will be available in future iPhone models. Bradford Betz, Fox News, "Apple bolsters iPhone security; says change aimed at blocking hackers, not law enforcement," 14 June 2018 The company also released a beta version of the upcoming iOS 12 that, according to Motherboard, all but kills off two iPhone unlocking tools used by police forces around the world. Dan Goodin, Ars Technica, "A host of new security enhancements is coming to iOS and macOS," 5 June 2018 Those who didn't pay to crowdfund the game can only play the early beta version of Hello Earth at Logan Arcade. Ryan Smith, Chicago Reader, "Animals / News / Technology / The Internet Famous feline Lil' Bub gets her own video game—built by Chicago's Logan Arcade," 23 May 2018 Meanwhile, Google also launched a beta version of its latest Android update even though less than 5% of the mobile operating system’s user base have upgraded to last year’s version. Dan Gallagher, WSJ, "Google Tries to Ease Its Tech Bottleneck," 9 May 2018 Exceed your limit, and Twitter's app icon will turn to gray on your home screen, and, at least in the beta version of Android P, Google's new mobile operating system, prevent you from opening the app. Robbie Gonzalez, WIRED, "The Research Behind Google's New Tools for Digital Well-Being," 9 May 2018 For more on AllGo, or to sign up for the beta version when it's released, visit Samantha Swindler,, "Oregon women's app will help plus-sized people navigate the world," 6 May 2018

Recent Examples on the Web: Adjective

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 Intel has issued beta patches for these, as well as some of the Arrandale and Clarkdale chips. Mark Hachman, PCWorld, "Intel issues Meltdown/Spectre fixes for Ivy Bridge, Sandy Bridge as patch effort winds down," 9 Mar. 2018 Long before Microsoft hoovered the game up in a multibillion-dollar deal and even before the game’s relatively popular beta version, Minecraft came to my attention through an innocuous post on Facebook. Steven Strom, Ars Technica, "One main mystery makes survival in Subnautica worthwhile," 27 Feb. 2018 Cherries are high in antioxidants and vitamin C, beta carotene, potassium, magnesium, iron, fiber and foliate. Indianapolis Star, "Cherry Recipes," 16 Feb. 2018 This is high in vitamins K and A, magnesium, beta carotene, B1, B2, B3, B5, B6, and folate. Kimberly Garrison,, "Healthy ways to combat the winter blahs," 12 Dec. 2017 Hunter's portrayal of Beth, a mother hell-bent on finding the best care (and partner) for her daughter, grounds the comedy, while Romano checks his TV shtick to play a beta father struggling with what to do. Andrea Mandell, USA TODAY, "Hey, Academy voters! Don't forget these Oscar-worthy performances," 18 Oct. 2017

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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Last Updated

7 Oct 2018

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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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Comments on beta

What made you want to look up beta? Please tell us where you read or heard it (including the quote, if possible).


a state of commotion or excitement

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