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

fateful \fate"ful\, a. .
   having the power of serving or accomplishing fate. "the
   fateful steel." --j. barlow.
   1913 webster

   2. significant of fate; ominous.
      1913 webster

            the fateful cawings of the crow.      --longfellow.
      -- fate"fully, adv.- fate"fulness, n.
      1913 webster
see also:
fate"fully fate"fulness 

[2] : WordNet (r) 2.0

fateful
     adj 1: having momentous consequences; of decisive importance; "that
            fateful meeting of the u.n. when...it declared war on
            north korea"- saturday rev; "the fatal day of the
            election finally arrived" syn: fatal
     2: of ominous significance syn: forebodinga, portentous
     3: of events having extremely unfortunate or dire
        consequences; bringing ruin; "the stock market crashed on
        black friday"; "a calamitous defeat"; "the battle was a
        disastrous end to a disastrous campaign"; "such doctrines,
        if true, would be absolutely fatal to my theory"- charles
        darwin; "it is fatal to enter any war without the will to
        win it"- douglas macarthur; "a fateful error" syn: black,
         calamitous, disastrous, fatal
     4: controlled or decreed by fate; predetermined; "a fatal
        series of events" syn: fatal
see also:
fatal forebodinga portentous black calamitous disastrous 

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

126 moby thesaurus words for "fateful":
   acute, apocalyptic, appointed, awe-inspiring, bad, baleful,
   baneful, black, bodeful, boding, calamitous, cataclysmal,
   cataclysmic, catastrophic, certain, conclusive, consequential,
   consuming, consumptive, critical, crucial, dark, deadly, decisive,
   demolishing, demolitionary, depredatory, desolating, destined,
   destroying, destructive, determinative, devastating, devoted, dire,
   direful, disastrous, doomed, doomful, dreary, earnest, evil,
   evil-starred, fatal, fated, foreboding, foredoomed, formidable,
   fratricidal, gloomy, grave, heavy, ill, ill-boding, ill-fated,
   ill-omened, ill-starred, important, imposing, in store,
   in the cards, inauspicious, indefeasible, ineluctable, inescapable,
   inevasible, inevitable, inexorable, inflexible, internecine,
   irresistible, irrevocable, lethal, lowering, major, marked,
   menacing, momentous, necessary, nihilist, nihilistic,
   of evil portent, ominous, ordained, pivotal, portending,
   portentous, ravaging, relentless, resistless, ruining, ruinous,
   self-destructive, serious, significant, sinister, sober, solemn,
   somber, subversionary, subversive, suicidal, sure, sure as death,
   sure as fate, threatening, unavoidable, uncontrollable,
   undeflectable, unfavorable, unfortunate, unlucky, unpreventable,
   unpromising, unpropitious, unstoppable, untoward, unyielding,
   vandalic, vandalish, vandalistic, wasteful, wasting, weighty,
   withering, written

Fateful >> F Words
Fateful, definition of term: Fateful
fateful_pag1.html