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

sudden \sud"den\, a. oe. sodian, sodein, of. sodain, sudain, f.
   soudain, l. subitaneus, fr. subitus sudden, that has come
   unexpectedly, p. p. of subire to come on, to steal upon; sub
   under, secretly + ire to go. see issue, and cf.
   subitaneous.
   1. happening without previous notice or with very brief
      notice; coming unexpectedly, or without the common
      preparation; immediate; instant; speedy. "o sudden wo"
      --chaucer. "for fear of sudden death." --shak.
      1913 webster

            sudden fear troubleth thee.           --job xxii.
                                                  10.
      1913 webster

   2. hastly prepared or employed; quick; rapid.
      1913 webster

            never was such a sudden scholar made. --shak.
      1913 webster

            the apples of asphaltis, appearing goodly to the
            sudden eye.                           --milton.
      1913 webster

   3. hasty; violent; rash; precipitate. obs. --shak.
      1913 webster

   syn: unexpected; unusual; abrupt; unlooked-for.
        1913 webster -- sud"denly, adv. -- sud"denness,
        n.
        1913 webster
see also:
issue subitaneous sud"denly sud"denness 

[2] : WordNet (r) 2.0

suddenly
     adv 1: happening unexpectedly; "suddenly she felt a sharp pain in
            her side" syn: all of a sudden, of a sudden
     2: quickly and without warning; "he stopped suddenly" syn: abruptly,
         short, dead
     3: on impulse; without premeditation; "he decided to go to
        chicago on the spur of the moment"; "he made up his mind
        suddenly" syn: on the spur of the moment
see also:
all of a sudden of a sudden abruptly short dead on the spur of the moment 

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

58 moby thesaurus words for "suddenly":
   a corps perdu, aback, abruptly, all at once, bang, by surprise,
   dash, feverishly, fleetingly, forthwith, hastily, head over heels,
   headfirst, headforemost, headlong, heels over head, hurriedly,
   impetuously, implausibly, improbably, impulsively, in a trice,
   instantaneously, instantly, like a flash, like a thunderbolt,
   momentarily, of a sudden, on short notice, plop, plump, plunk, pop,
   precipitantly, precipitately, precipitously, quickly, rapidly,
   rashly, recklessly, sharp, short, slap, slap-bang, smack, speedily,
   startlingly, sudden, surprisingly, swiftly, unanticipatedly,
   unaware, unawares, unexpectedly, unforeseeably, unpredictably,
   without notice, without warning

Suddenly >> S Words
Suddenly, definition of term: Suddenly
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