The Collaborative International Dictionary of English v.0.48:

Confound \Con*found"\ (k[o^]n*found"), v. t. [imp. & p. p.
   Confounded; p. pr. & vb. n. Confounding.] [F. confondre,
   fr. L. confundere, -fusum, to pour together; con- + fundere
   to pour. See Fuse to melt, and cf. Confuse.]
   1. To mingle and blend, so that different elements can not be
      distinguished; to confuse.
      [1913 Webster]

            They who strip not ideas from the marks men use for
            them, but confound them with words, must have
            endless dispute.                      --Locke.
      [1913 Webster]

            Let us go down, and there confound their language.
                                                  --Gen. xi. 7.
      [1913 Webster]

   2. To mistake for another; to identify falsely.
      [1913 Webster]

            They [the tinkers] were generally vagrants and
            pilferers, and were often confounded with the
            gypsies.                              --Macaulay.
      [1913 Webster]

   3. To throw into confusion or disorder; to perplex; to strike
      with amazement; to dismay.
      [1913 Webster]

            The gods confound...
            The Athenians both within and out that wall. --Shak.
      [1913 Webster]

            They trusted in thee and were not confounded. --Ps.
                                                  xxii. 5.
      [1913 Webster]

            So spake the Son of God, and Satan stood
            A while as mute, confounded what to say. --Milton.
      [1913 Webster]

   4. To destroy; to ruin; to waste. [Obs.]
      [1913 Webster]

            One man's lust these many lives confounds. --Shak.
      [1913 Webster]

            How couldst thou in a mile confound an hour? --Shak.

   Syn: To abash; confuse; baffle; dismay; astonish; defeat;
        terrify; mix; blend; intermingle. See Abash.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

confounding \confounding\ adj.
   tending to contradict (a hypothesis).

   Syn: contradictory.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

confounding \confounding\ n.
   a mistake that results from taking one thing to be another.

   Syn: confusion, mix-up.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

confounding
    adj 1: that confounds or contradicts or confuses [syn:
           confounding, contradictory]