Source : Webster's Revised Unabridged Dictionary (1913)

Startle \Star"tle\, v. t. [imp. & p. p. {Startled}; p. pr. & vb.
   n. {Startling}.] [Freq. of start.]
   To move suddenly, or be excited, on feeling alarm; to start.

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

Source : WordNet®

startling
     adj : so remarkably different or sudden as to cause momentary
           shock or alarm; "Sydney's startling new Opera House";
           "startling news"; "startling earthquake shocks"