Source : Webster's Revised Unabridged Dictionary (1913)

Prohibitive \Pro*hib"it*ive\, a. [Cf. F. prohibitif.]
   That prohibits; prohibitory; as, a tax whose effect is
   prohibitive.

Source : WordNet®

prohibitive
     adj : tending to discourage (especially of prices); "the price was
           prohibitive" [syn: {prohibitory}]