I. ˈbā-tə, chiefly Brit ˈbē- noun
Etymology: Middle English betha, from Latin beta, from Greek bēta, of Semitic origin; akin to Hebrew bēth beth
Date: 14th century
1. : the 2d letter of the Greek alphabet — see alphabet table
2. : beta particle
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 (as software)
released in beta
the beta version
II. adjective
Date: 1862
: second in position in the structure of an organic molecule from a particular group or atom
beta substitution
— often used in combination; symbol β