disjunctive

adj. tending to separate; expressing an oppositional relationship between two words (Grammar)

n. (Grammar) conjunction that expresses an oppositional relationship between two items (i.e. "or" in the phrase "one or the other")

In logic and mathematics, or, also known as logical disjunction or inclusive disjunction is a logical operator that results in true whenever one or more of its operands are true. In grammar, or is a coordinating conjunction.
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(n.)
A disjunctive proposition.
  

(n.)
A disjunctive conjunction.
  

(a.)
Tending to disjoin; separating; disjoining.
  

(a.)
Pertaining to disjunct tetrachords.
  

Adjective
1. serving or tending to divide or separate
(antonym) conjunctive
(similar) adversative, oppositive