<p><strong>Noun</strong></p><ul><li>the second letter of the Greek alphabet (β, B).</li><li>the consonant sound represented by the second letter of the Greek alphabet.</li><li>Beta, Astronomy: a star that is usually the second brightest of a constellation: The second brightest star in Taurus is Beta Tauri.</li><li>Chemistry: one of the possible positions of an atom or group in a compound.</li><li>one of two or more isomeric compounds.</li><li>the second of any series, as in chemistry or physics.</li><li>Computers: the phase of hardware or software development in which a product is tested in the environment for which it was designed: beta test.</li><li>an arbitrary measure of the volatility of a given stock using an index of the volatility of the market as a whole: A beta of 1.1 indicates a stock that is 10 percent more volatile than the market.</li><li>a brand of tape format for VCR tape, incompatible with other formats.</li><li>chiefly British: a grade showing that a student is in the middle or second of three scholastic sections in a class.</li><li>beta male.</li></ul><p><strong>Adjective</strong></p><ul><li>Computers: being, relating to, or undergoing the phase of product development in which a product is tested in the environment for which it was designed: beta test.</li><li>(of an animal) having the second-highest rank in a dominance hierarchy: the beta female in a pack of meerkats.</li><li>Slang: sometimes disparaging, being or relating to a man who is perceived to be weak, mild-mannered, and unimpressive.</li></ul>