Source : Webster's Revised Unabridged Dictionary (1913)

Contraries \Con"tra*ries\ (? or ?; 48), n. pl. [Pl. of
   {Contrary}, n.] (Logic)
   Propositions which directly and destructively contradict each
   other, but of which the falsehood of one does not establish
   the truth of the other.

         If two universals differ in quality, they are
         contraries; as, every vine is a tree; no vine is a
         tree. These can never be both true together; but they
         may be both false.                       --I. Watts.

Contrary \Con"tra*ry\, n.; pl. {Contraries}.
   1. A thing that is of contrary or opposite qualities.

            No contraries hold more antipathy Than I and such a
            knave.                                --Shak.

   2. An opponent; an enemy. [Obs.] --Chaucer.

   3. the opposite; a proposition, fact, or condition
      incompatible with another; as, slender proofs which rather
      show the contrary. See {Converse}, n., 1. --Locke.

   4. (Logic) See {Contraries}.

   {On the contrary}, in opposition; on the other hand. --Swift.

   {To the contrary}, to an opposite purpose or intent; on the
      other side. ``They did it, not for want of instruction to
      the contrary.'' --Bp. Stillingfleet.