The Collaborative International Dictionary of English v.0.48:

Interpretative \In*ter"pre*ta*tive\, a. [Cf. F.
   interpr['e]tatif.]
   [1913 Webster]
   1. Designed or fitted to interpret; explanatory.
      "Interpretative lexicography." --Johnson.
      [1913 Webster]

   2. According to interpretation; constructive.
      [1913 Webster]

            An interpretative siding with heresies. --Hammond.
      [1913 Webster]

WordNet (r) 3.0 (2006):

interpretative
    adj 1: that provides interpretation [syn: interpretative,
           interpretive]