The Collaborative International Dictionary of English v.0.48:

Terrify \Ter"ri*fy\, v. t. [imp. & p. p. Terrified; p. pr. &
   vb. n. Terrifying.] [L. terrere to frighten + -fy: cf. F.
   terrifier, L. terrificare. See Terrific, and -fy.]
   1. To make terrible. [Obs.]
      [1913 Webster]

            If the law, instead of aggravating and terrifying
            sin, shall give out license, it foils itself.
                                                  --Milton.
      [1913 Webster]

   2. To alarm or shock with fear; to frighten.
      [1913 Webster]

            When ye shall hear of wars . . . be not terrified.
                                                  --Luke xxi. 9.
      [1913 Webster]

WordNet (r) 3.0 (2006):

terrify
    v 1: fill with terror; frighten greatly [syn: terrify,
         terrorize, terrorise]

Moby Thesaurus II by Grady Ward, 1.0:

21 Moby Thesaurus words for "terrify":
   affright, alarm, appall, awe, freeze, fright, frighten, horrify,
   paralyze, petrify, scare, scare stiff, scare to death, shock,
   spook, startle, strike dumb, strike terror into, stun, stupefy,
   terrorize