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

Noun a program that is currently in beta
Recent Examples on the Web: Noun Vitamin C-rich fruits (oranges, grapefruit, etc.) are also good, as are beta-carotene–rich carrots. Barbara Brody, Better Homes & Gardens, "Eye Doctors Debunk 5 Common Myths (Plus, 3 Ways to Keep Your Eyes Healthy)," 7 Apr. 2020 Moderate alcohol consumption is associated with reduced levels of beta amyloid, the protein that forms the brain plaques of Alzheimer’s disease, a new study suggests. Nicholas Bakalar, New York Times, "Moderate Drinking Tied to Lower Levels of Alzheimer’s Brain Protein," 5 Mar. 2020 The decline was three times as fast for those with existing beta-amyloid plaques. Sandee Lamotte, CNN, "Widowhood increases risk of Alzheimer's, study says," 26 Feb. 2020 On Wednesday, Apple released the developer beta of iOS 13.5 with updates to Face ID and Group FaceTime, the company told USA TODAY via email. Coral Murphy, USA TODAY, "Developer beta for next iOS update helps iPhone users unlock phones with face masks," 30 Apr. 2020 Reuters/Shannon Stapleton On April 22, Utah Governor Gary Herbert announced the beta release of an app that will help the state trace the contacts of those infected with Covid-19. Amrita Khalid, Quartz, "Utah’s new Covid-19 contact tracing app will track user locations," 23 Apr. 2020 The acetyl glycyl beta-alanine ingredient in the formula stood out to Jaliman, who says this peptide will probably help lighten the pigment of a scar while also working to even out skin tone. Maya Gandara,, "Shoppers Swear By Derma-E’s Scar Gel For Healing Stubborn Acne Marks," 15 Apr. 2020 On Tuesday morning, as the beta went live, were watching it on Twitch — a historic figure that had swelled to over later that day. Ethan Davison, Washington Post, "Valorant’s super-fast servers are attracting streamers and pros in droves. Here’s why.," 14 Apr. 2020 An open beta for the game started on January 24 and is now set to end as the game gears up for its April 30 launch. Michael Koczwara, The Hollywood Reporter, "Mobile Games Hotspot: 'Pokemon Go' Debuts Leaderboards; 'Fortnite' Maker Unveils New Title," 9 Apr. 2020 Recent Examples on the Web: Adjective Several executives, including Janice Min, left Quibi during its beta phase, and the company parted with another key team member in recent weeks: Megan Imbres, the top marketing executive, who declined to comment. Nicole Sperling, New York Times, "Jeffrey Katzenberg Blames Pandemic for Quibi’s Rough Start," 11 Apr. 2020 WhatsApp Pay began beta testing two years ago but hasn’t been launched yet. Ananya Bhattacharya, Quartz India, "One table that shows how massive the Facebook-Reliance Jio universe can be," 29 Apr. 2020 But what was shown is nearly identical to the beta vehicles Lucid has been showing off—albeit shinier and with a proper interior. Roberto Baldwin, Car and Driver, "Lucid Shows 400-Mile-Range Air Electric Sedan to Future Owners," 14 Feb. 2020 Because beta blockers cause a direct decrease in heart rate, this patient population may have a slower heart rate than would be typical for an untreated patient group, resulting in an underestimation of true AFib heart rates for a larger population. John Nosta, Fortune, "Should consumers be wary of Apple’s heartbeat monitoring app?," 26 Feb. 2020 But how beta-amyloid leads to the devastation of tau has never been precisely clear. Karen Weintraub, Scientific American, "Possible Missing Link in Alzheimer’s Pathology Identified," 16 Jan. 2020 The service, which has been beta testing for the last year, is aimed at providing content that keeps readers coming back instead of running away to avoid ads. Nathan Bomey, USA TODAY, "Gannett-backed Scroll launches subscription service for ad-free journalism," 28 Jan. 2020 Genetically modifying rice to contain beta carotene is at best a band-aid for extreme cases of VAD, not a corrective for a widespread problem. Dominic Glover, The Conversation, "The Philippines has rated ‘Golden Rice’ safe, but farmers might not plant it," 7 Feb. 2020 Now in beta phase, Eke says Rise already has over 1,000 users. Yomi Kazeem, Quartz Africa, "Fintech startups are making it easier for Nigerian millennials to invest in US stocks," 16 Jan. 2020

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.

See More

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

Keep scrolling for more

Learn More about beta

Time Traveler for beta

Time Traveler

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

See more words from the same century

Statistics for beta

Last Updated

19 May 2020

Cite this Entry

“Beta.” Dictionary, Merriam-Webster, Accessed 29 May. 2020.

Keep scrolling for more

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


How to pronounce beta (audio)

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
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

Keep scrolling for more

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

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).


See Definitions and Examples »

Get Word of the Day daily email!

Test Your Vocabulary

May 2020 Words of the Day Quiz

  • a blooming wisteria tree
  • Which is a synonym of exiguous?
Spell It

Can you spell these 10 commonly misspelled words?


Test Your Knowledge - and learn some interesting things along the way.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!