beta

1 of 2

noun

be·​ta ˈbā-tə 

chiefly British

ˈbē- 

plural betas

1

: the 2nd letter of the Greek alphabet see Alphabet Table

2

a

: something or someone designated with the name beta or the Greek letter β especially denoting the second in position, order, or class

b

slang, disparaging : a timid, weak, or submissive person

… [he] is still such a beta he doesn't do solo press conferences.

—Dieter Kurtenbach

compare alpha entry 1 sense 6, sigma

3

: 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

The app is still in beta.

compare alpha entry 1 sense 5

4

: beta particle

beta emissions

5

: 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

Beta measures a stock's price volatility—or risk—compared with the market in general …

—Marlys J. Harris

6

: beta wave

The findings could also help scientists better understand other beta-associated disorders, such as Parkinson's disease or obsessive compulsive disorder …

—Brown University

beta

2 of 2

adjective

1

: second in position in the structure of an organic molecule from a particular group or atom

beta substitution

—often used in combination

—symbol β

2

slang, disparaging : socially submissive or subordinate : having the character, qualities, or status of a beta

a beta male

Examples of beta in a Sentence

Noun

a program that is currently in beta

Recent Examples on the Web

Noun

While in beta, Perplexity Patents will be free for all users, but Pro and Max subscribers will receive additional usage quotas and model configuration options. —PC Magazine, 1 Nov. 2025

Housed within the Delta app, the October 29 Delta Concierge beta release delivers real-time, personalizes support to SkyMiles Members. —Eileen Falkenberg-Hull, MSNBC Newsweek, 31 Oct. 2025

Adjective

Advertisement Meanwhile, beta blocker medications tend to reduce REM sleep, which is when most dreaming occurs, but research has found that they are associated with an increase in nightmares. —Stacey Colino, Time, 3 Nov. 2025

The presence of beta amyloid and tau proteins are hallmark signs of Alzheimer’s. —Sandee Lamotte, CNN Money, 3 Nov. 2025

Word History

Etymology

Noun

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

First Known Use

Noun

14th century, in the meaning defined at sense 1

Adjective

1862, in the meaning defined at sense 1

Phrases Containing beta

• A-beta
• amyloid beta
• amyloid beta peptide
• amyloid beta protein
• beta-adrenergic
• beta-amyloid
• beta-amyloid peptide
• beta-amyloid protein
• beta-blocker
• beta-carotene
• beta cell
• beta decay
• beta-endorphin
• beta globulin
• beta-glucan
• beta hydroxy acid
• beta interferon
• beta-lactamase
• beta-oxidation
• beta particle
• beta ray
• beta-receptor
• beta test
• beta-thalassemia
• beta wave
• interferon beta

Rhymes for beta

• data
• theta
• zeta
• oligochaeta
• peseta
• punctata
• polychaeta

Kids Definition

beta

noun

be·​ta

ˈbāt-ə

: the 2nd letter of the Greek alphabet

—Β or β

Medical Definition

beta

1 of 2 noun

be·​ta

ˈbāt-ə, chiefly British ˈbē-tə

1

: the second letter of the Greek alphabet

—symbol Β or β

2

: beta particle

3

: beta wave

beta

2 of 2 adjective

variants or β-

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