The Collaborative International Dictionary of English v.0.48:

evasive \e*va"sive\ ([-e]*v[=a]"s[i^]v), a. [Cf. F. ['e]vasif.
   See Evade.]
   Tending to evade, or marked by evasion; elusive; shuffling;
   avoiding by artifice.
   [1913 Webster]

         Thus he, though conscious of the ethereal guest,
         Answered evasive of the sly request.     --Pope.
   [1913 Webster]

         Stammered out a few evasive phrases.     --Macaulay.
   -- E*va"sive*ly, adv. -- E*va"sive*ness, n.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

evasiveness \e*va"siv*eness\ ([-e]*v[=a]"s[i^]v*n[e^]s), n.
   Deliberate vagueness or ambiguity; failing to answer a
   question while trying to seem as though one is answering.

   Syn: equivocation.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

evasiveness
    n 1: intentionally vague or ambiguous [syn: equivocation,
         prevarication, evasiveness]