binary arithmetic operation
         n 1: an operation that follows the rules of Boolean algebra;
               each operand and the result take one of two values [syn:
               {boolean operation}, {binary operation}, {binary arithmetic
               operation}]

English Dictionary: binary arithmetic operation	by the DICT Development Group
From Webster's Revised Unabridged Dictionary (1913) [web1913]:
Binary \Bi"na*ry\, a. [L. binarius, fr. bini two by two, two at       a time, fr. root of bis twice; akin to E. two: cf. F.       binaire.]       Compounded or consisting of two things or parts;       characterized by two (things).          {Binary arithmetic}, that in which numbers are expressed             according to the binary scale, or in which two figures             only, 0 and 1, are used, in lieu of ten; the cipher             multiplying everything by two, as in common arithmetic by             ten. Thus, 1 is one; 10 is two; 11 is three; 100 is four,             etc. --Davies & Peck.          {Binary compound} (Chem.), a compound of two elements, or of             an element and a compound performing the function of an             element, or of two compounds performing the function of             elements.          {Binary logarithms}, a system of logarithms devised by Euler             for facilitating musical calculations, in which 1 is the             logarithm of 2, instead of 10, as in the common             logarithms, and the modulus 1.442695 instead of .43429448.                      {Binary measure} (Mus.), measure divisible by two or four;             common time.          {Binary nomenclature} (Nat. Hist.), nomenclature in which the             names designate both genus and species.          {Binary scale} (Arith.), a uniform scale of notation whose             ratio is two.          {Binary star} (Astron.), a double star whose members have a             revolution round their common center of gravity.          {Binary theory} (Chem.), the theory that all chemical             compounds consist of two constituents of opposite and             unlike qualities.