The Collaborative International Dictionary of English v.0.48:

Responsive \Re*spon"sive\ (-s?v), a. [Cf. F. resposif.]
   1. That responds; ready or inclined to respond.
      [1913 Webster]

   2. Suited to something else; correspondent.
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            The vocal lay responsive to the strings. --Pope.
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   3. Responsible. [Obs.] --Jer. Taylor.
      [1913 Webster] -- Re*spon"sive*ly, adv. --
      Re*spon"sive*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

responsiveness
    n 1: responsive to stimulation [syn: responsiveness,
         reactivity]
    2: the quality of being responsive; reacting quickly; as a
       quality of people, it involves responding with emotion to
       people and events [ant: deadness, unresponsiveness]