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

The invite-only beta of the Room418 app will launch later this fall ahead of the company’s commercial rollout. — Jesse Whittock, Deadline, 2 Oct. 2026

This is all just a preview for now because ordering by text isn’t available yet — iOS users in the US can join a waitlist from today to try the experience in beta. — Jess Weatherbed, The Verge, 30 Sep. 2026

Adjective

An invite-only beta version of the Room418 app will launch this fall ahead of a commercial launch, featuring a slate of licensed horror content. — Jesse Whittock, Deadline, 2 Oct. 2026

The beta version, which was soft-launched this week, is still under development and will continue to evolve in the coming months, NIH officials told STAT. — Megan Molteni, STAT, 2 Oct. 2026

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
• advaita
• peseta
• punctata
• oligochaeta
• polychaeta
• radiata

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