horrendous

from WordNet (r) 3.0 (2006)

horrendous
    adj 1: causing fear or dread or terror; "the awful war"; "an
           awful risk"; "dire news"; "a career or vengeance so
           direful that London was shocked"; "the dread presence of
           the headmaster"; "polio is no longer the dreaded disease
           it once was"; "a dreadful storm"; "a fearful howling";
           "horrendous explosions shook the city"; "a terrible
           curse" [syn: {awful}, {dire}, {direful}, {dread(a)},
           {dreaded}, {dreadful}, {fearful}, {fearsome},
           {frightening}, {horrendous}, {horrific}, {terrible}]

from The Collaborative International Dictionary of English v.0.48

Horrendous \Hor*ren"dous\, a. [L. horrendus.]
   Fearful; frightful. [Obs.] --I. Watts.
   [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

36 Moby Thesaurus words for "horrendous":
      appalling, astounding, atrocious, awe-inspiring, awesome, awful,
      baneful, beastly, dire, direful, dread, dreaded, dreadful, fell,
      formidable, ghastly, ghoulish, grim, grisly, gruesome, hideous,
      horrible, horrid, horrific, horrifying, macabre, morbid,
      redoubtable, rotten, schrecklich, shocking, terrible, terrific,
      tragic, tremendous, unspeakable