The Collaborative International Dictionary of English v.0.48:

Discretive \Dis*cre"tive\, a. [L. discretivus. See Discrete.]
   Marking distinction or separation; disjunctive.
   [1913 Webster]

   Discretive proposition (Logic & Gram.), one that expresses
      distinction, opposition, or variety, by means of
      discretive particles, as but, though, yet, etc.; as,
      travelers change their climate, but not their temper.
      [1913 Webster]