/dis jungk"sheuhn/ , n.
1. the act of disjoining or the state of being disjoined: a disjunction between thought and action.
2. Logic.
a. Also called disjunctive, inclusive disjunction . a compound proposition that is true if and only if at least one of a number of alternatives is true.
b. Also called exclusive disjunction . a compound proposition that is true if and only if one and only one of a number of alternatives is true.
c. the relation among the components of such a proposition, usually expressed by AND or V.
[ 1350-1400; ME disjunccioun disjunction- (s. of disjunctio ) separation, equiv. to disjunct ( us ) (see DISJUNCT) + -ion- -ION ]