the second letter of the Greek alphabet (β, B).
the consonant sound represented by the second letter of the Greek alphabet.
Astronomy. Beta, a star that is usually the second brightest of a constellation.
The second brightest star in Taurus is Beta Tauri.
Chemistry.
one of the possible positions of an atom or group in a compound.
one of two or more isomeric compounds.
the second of any series, as in chemistry or physics.
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.
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.
Trademark. Beta, a brand of tape format for VCR tape, incompatible with other formats.
Chiefly British. a grade showing that a student is in the middle or second of three scholastic sections in a class.
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.
(of an animal) having the second-highest rank in a dominance hierarchy.
the beta female in a pack of meerkats.
Slang: Sometimes Disparaging. being or relating to a man who is perceived to be weak, mild-mannered, and unimpressive.
the second letter in the Greek alphabet (Β, β), a consonant, transliterated as b
the second highest grade or mark, as in an examination
(modifier)
involving or relating to electrons
beta emitter
relating to one of two or more allotropes or crystal structures of a solid
beta iron
relating to one of two or more isomeric forms of a chemical compound
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
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.
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
The “Low Beta Anomaly” was first discovered in the 1970s and contradicted a bedrock stock-pricing model.
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
What’s Next: Spark has begun rolling out to testers, with the Beta expected to go out to Google AI Ultra subscribers in the U.S. next week.
From Barron's • May 20, 2026
The Goldman Sachs High Beta Momentum Long Index has just had its second biggest 18-day run in history, he says.
From MarketWatch • Apr. 24, 2026
When the Science Patrol encountered a threat they couldn’t handle on their own, Hayata would use an alien device called a Beta Capsule to transform into an alien superbeing known as Ultraman.
From "Ready Player One: A Novel" by Ernest Cline
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.
