The Collaborative International Dictionary of English v.0.48:

Rattle \Rat"tle\ (r[a^]t"t'l), v. i. [imp. & p. p. Rattled
   (-t'ld); p. pr. & vb. n. Rattling (-tl[i^]ng).] [Akin to D.
   ratelen, G. rasseln, AS. hr[ae]tele a rattle, in
   hr[ae]telwyrt rattlewort; cf. Gr. kradai`nein to swing, wave.
   Cf. Rail a bird.]
   1. To make a quick succession of sharp, inharmonious noises,
      as by the collision of hard and not very sonorous bodies
      shaken together; to clatter.
      [1913 Webster]

            And the rude hail in rattling tempest forms.
                                                  --Addison.
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            'T was but the wind,
            Or the car rattling o'er the stony street. --Byron.
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   2. To drive or ride briskly, so as to make a clattering; as,
      we rattled along for a couple of miles. [Colloq.]
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   3. To make a clatter with the voice; to talk rapidly and
      idly; to clatter; -- with on or away; as, she rattled on
      for an hour. [Colloq.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

rattled
    adj 1: thrown into a state of agitated confusion; (`rattled' is
           an informal term) [syn: flustered, hot and
           bothered(p), perturbed, rattled]