Source : Webster's Revised Unabridged Dictionary (1913)

Regressive \Re*gress"ive\ (r?*gr?s"?v), a. [Cf. F.
   r['e]gressif.]
   1. Passing back; returning.

   2. Characterized by retrogression; retrogressive.

   {Regressive metamorphism}.
      (a) (Biol.) See {Retrogression}.
      (b) (Physiol.) See {Katabolism}.

Source : WordNet®

regressive
     adj 1: (of taxes) adjusted so that the rate decreases as the amount
            increases [ant: {progressive}]
     2: opposing progress [ant: {progressive}]