The Collaborative International Dictionary of English v.0.48:

Startle \Star"tle\ (st[aum]r"t'l), v. i. [imp. & p. p.
   Startled (st[aum]r"t'ld); p. pr. & vb. n. Startling
   (st[aum]r"tl[i^]ng).] [Freq. of start.]
   To move suddenly, or be excited, on feeling alarm; to start.
   [1913 Webster]

         Why shrinks the soul
         Back on herself, and startles at destruction?
                                                  --Addison.
   [1913 Webster]

WordNet (r) 3.0 (2006):

startled
    adj 1: excited by sudden surprise or alarm and making a quick
           involuntary movement; "students startled by the teacher's
           quiet return"; "the sudden fluttering of the startled
           pigeons"; "her startled expression"

Moby Thesaurus II by Grady Ward, 1.0:

20 Moby Thesaurus words for "startled":
   affrighted, alarmed, alerted, aroused, bowled down, consternated,
   daunted, dismayed, disquieted, electrified, frightened,
   in a fright, in a funk, jarred, jolted, shaken, shocked, shook,
   staggered, taken aback