Толковый словарь английского языка - beta

I. noun Etymology: Middle English betha, from Latin ~, from Greek bēta, of Semitic origin; akin to Hebrew bēth beth Date: 14th century the 2d letter of the Greek alphabet, ~ particle, 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, a nearly complete prototype of a product (as software) , II. adjective Date: 1862 second in position in the structure of an organic molecule from a particular group or atom