[syn: terrific, terrifying]
The Collaborative International Dictionary of English v.0.48:
Terrific \Ter*rif"ic\, a. [L. terrificus; fr. terrere to
   frighten + facere to make. See Terror, and Fact.]
   Causing terror; adapted to excite great fear or dread;
   terrible; as, a terrific form; a terrific sight.
   [1913 Webster]
WordNet (r) 3.0 (2006):
terrific
    adj 1: very great or intense; "a terrific noise"; "a terrific
           thunderstorm storm"; "fought a terrific battle"
    2: extraordinarily good or great ; used especially as
       intensifiers; "a fantastic trip to the Orient"; "the film was
       fantastic!"; "a howling success"; "a marvelous collection of
       rare books"; "had a rattling conversation about politics"; "a
       tremendous achievement" [syn: fantastic, grand,
       howling(a), marvelous, marvellous, rattling(a),
       terrific, tremendous, wonderful, wondrous]
    3: causing extreme terror; "a terrifying wail" [syn: terrific,
       terrifying]
Moby Thesaurus II by Grady Ward, 1.0:
82 Moby Thesaurus words for "terrific":
   ace, agitating, appalling, astounding, awe-inspiring, awesome,
   awful, breathtaking, deadly, dire, direful, disquieting, divine,
   dread, dreaded, dreadful, excellent, exceptional, exquisite,
   extraordinary, fabulous, fantastic, fearful, fell, first-class,
   formidable, frightful, ghastly, ghoulish, gilt-edged, glorious,
   golden, great, grim, grisly, groovy, gruesome, heavenly, hideous,
   horrendous, horrible, horrid, horrific, horrifying, hot, howling,
   immense, incredible, keen, macabre, magnificent, marvelous,
   mind-boggling, morbid, outstanding, rattling, redoubtable, rousing,
   schrecklich, screaming, sensational, shocking, smashing, splendid,
   splendiferous, sterling, stupendous, super, superb, supereminent,
   superexcellent, superfine, superior, swell, terrible, terrorizing,
   thumping, tremendous, unbelievable, upsetting, whacking,
   wonderful