(Alg.) A number, letter, or any quantity written on the right hand of and above another quantity, and denoting how many times the latter is repeated as a factor to produce the power indicated; Note: thus a^(2) denotes the second power, and a^(x) the xth power, of a (2 and x being the exponents). A fractional exponent, or index, is used to denote the root of a quantity. Thus, a^(1/3) denotes the third or cube root of a.