Terrifying

terrifying
    adj 1: causing extreme terror; "a terrifying wail" [syn:
           {terrific}, {terrifying}]
    

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.
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   2. To alarm or shock with fear; to frighten.
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            When ye shall hear of wars . . . be not terrified.
                                                  --Luke xxi. 9.
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30 Moby Thesaurus words for "terrifying":
      alarming, bloodcurdling, frightening, grim, grisly, gruesome,
      hair-raising, hideous, horrible, horrid, horrifying, macabre,
      paralyzing, petrifying, scary, shocking, stunning, stupefying,
      terrible, terror, terror-bearing, terror-breathing,
      terror-breeding, terror-bringing, terror-fraught, terror-giving,
      terror-inspiring, terror-striking, terrorful, terroristic