Exclusive or

(XOR, EOR) /X or, E or/ A two-input Boolean logic function whose result is true if one input is true and the other is false. The output is thus true if the inputs are not equal. If one input is false, the other is passed unchanged whereas if one input is true, the other is inverted. In Boolean algebra, exclusive or is often written as a plus in a circle: "⊕". The circle may be omitted suggesting addition modulo two.

Free Online Dictionary of Computing