1. 
[syn: atrocious, frightful, horrifying, horrible, ugly]
The Collaborative International Dictionary of English v.0.48:
Horrify \Hor"ri*fy\, v. t. [imp. & p. p. Horrified; p. pr. &
   vb. n. Horrifying.] [L. horrificare. See Horrific.]
   To cause to feel horror; to strike or impress with horror;
   as, the sight horrified the beholders. --E. Irving.
   [1913 Webster]
WordNet (r) 3.0 (2006):
horrifying
    adj 1: provoking horror; "an atrocious automobile accident"; "a
           frightful crime of decapitation"; "an alarming, even
           horrifying, picture"; "war is beyond all words horrible"-
           Winston Churchill; "an ugly wound" [syn: atrocious,
           frightful, horrifying, horrible, ugly]
Moby Thesaurus II by Grady Ward, 1.0:
38 Moby Thesaurus words for "horrifying":
   appalling, astounding, atrocious, awe-inspiring, awesome, awful,
   baneful, beastly, dire, direful, dread, dreaded, dreadful, fell,
   formidable, ghastly, ghoulish, grim, grisly, gruesome, hideous,
   horrendous, horrible, horrid, horrific, lurid, macabre, morbid,
   redoubtable, rotten, schrecklich, shocking, terrible, terrific,
   terrifying, tragic, tremendous, unspeakable