The Jargon File (version 4.4.7, 29 Dec 2003):

xor
 /X'or/, /kzor/, conj.

    Exclusive or. ?A xor B? means ?A or B, but not both?. ?I want to get cherry
    pie xor a banana split.? This derives from the technical use of the term as
    a function on truth-values that is true if exactly one of its two arguments
    is true.


The Free On-line Dictionary of Computing (30 December 2018):

exclusive or
EOR
xor

    (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 truth table is

   	A | B | A xor B
   	--+---+--------
   	F | F |    F
   	F | T |    T
   	T | F |    T
   	T | T |    F

   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.

   In digital logic, an exclusive or logic gate is drawn like
   a normal inclusive or gate but with a curved line across
   both inputs:
   exclusive or gate
   (img:http://upload.wikimedia.org/wikipedia/commons/e/e0/XOR.jpg).

   (2006-12-13)