[1] : The Collaborative International Dictionary of English v.0.48

tremendous \tremen"dous\, a. l. tremendus that is to be
   trembled at, fearful, fr. tremere to tremble. see tremble.
   fitted to excite fear or terror; such as may astonish or
   terrify by its magnitude, force, or violence; terrible;
   dreadful; as, a tremendous wind; a tremendous shower; a
   tremendous shock or fall.
   1913 webster

         a tremendous mischief was a foot.        --motley.
   1913 webster

   syn: terrible; dreadful; frightful; terrific; horrible;
        awful.
        1913 webster -- tremen"dously, adv. --
        tremen"dousness, n.
        1913 webster
see also:
tremble tremen"dously tremen"dousness 

[2] : WordNet (r) 2.0

tremendous
     adj 1: extraordinarily large in size or extent or amount or power
            or degree; "an enormous boulder"; "enormous expenses";
            "tremendous sweeping plains"; "a tremendous fact in
            human experience; that a whole civilization should be
            dependent on technology"- walter lippman; "a plane
            took off with a tremendous noise" syn: enormous
     2: extraordinarily good; 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, howlinga, marvelous,
         marvellous, rattlinga, terrific, wonderful, wondrous
see also:
enormous fantastic howlinga marvelous marvellous rattlinga 
terrific wonderful wondrous 

[3] : Moby Thesaurus II by Grady Ward, 1.0

104 moby thesaurus words for "tremendous":
   atlantean, brobdingnagian, cyclopean, gargantuan, herculean,
   homeric, abysmal, amazing, amplitudinous, appalling, astounding,
   astronomic, astronomical, awe-inspiring, awesome, awful, boundless,
   bulky, colossal, cosmic, cracking, dire, direful, divine, dread,
   dreaded, dreadful, elephantine, enormous, epic, exquisite,
   extensive, fantastic, fell, flabbergasting, formidable, frightful,
   galactic, ghastly, ghoulish, giant, giantlike, gigantic,
   gilt-edged, glorious, golden, grim, grisly, gruesome, heavenly,
   heroic, hideous, horrendous, horrible, horrid, horrific,
   horrifying, huge, immeasurable, immense, infinite, jumbo,
   king-size, large, macabre, magnificent, mammoth, marvelous,
   massive, massy, mighty, monster, monstrous, monumental, morbid,
   mortal, mountainous, outsize, overgrown, prodigious, profound,
   redoubtable, schrecklich, sensational, shocking, sizable, spacious,
   splendid, splendiferous, sterling, stupendous, super, superb,
   supereminent, superexcellent, superfine, terrible, terrific,
   titanic, towering, vast, voluminous, weighty, wonderful

Tremendous >> T Words
Tremendous, definition of term: Tremendous
tremendous_pag1.html