The Collaborative International Dictionary of English v.0.48:

obviating \obviating\ adj. pren.
   making impossible or unnecessary.

   Syn: preclusive.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Obviate \Ob"vi*ate\, v. t. [imp. & p. p. Obviated; p. pr. &
   vb. n. Obviating.] [L. obviare; ob (see Ob-) + viare to
   go, fr. via way. See Voyage.]
   [1913 Webster]
   1. To meet in the way. [Obs.]
      [1913 Webster]

            Not to stir a step to obviate any of a different
            religion.                             --Fuller.
      [1913 Webster]

   2. To anticipate; to prevent by interception; to remove from
      the way or path; to make unnecessary; as, to obviate the
      necessity of going.
      [1913 Webster]

            To lay down everything in its full light, so as to
            obviate all exceptions.               --Woodward.
      [1913 Webster]

WordNet (r) 3.0 (2006):

obviating
    adj 1: made impossible [syn: preclusive, obviating(a)]