beta

noun

• the second letter of the Greek alphabet (Β, β), transliterated as ‘b’.
• [as modifier] denoting the second of a series of items, categories, forms of a chemical compound, etc.:beta carotene beta blocker
• British a second-class mark given for a piece of work or an examination paper.
• informalshort for beta test.
• (Beta) [followed by Latin genitive] Astronomy the second (typically second-brightest) star in a constellation:Beta Virginis
• [as modifier] relating to beta decay or beta particles:beta emitters
• (also beta coefficient) a measure of the movement in price of a security relative to the stock market as a whole, used to indicate possible risk: a fund with a beta of 0.58 is less volatile