WordWeb Online

1. Surprising greatly
   "the dog was capable of astonishing tricks"
   - amazing
    
2. So surprisingly impressive as to stun or overwhelm
   "such an enormous response was astonishing"
   - astounding, staggering, stupefying

1. Affect with wonder
   - amaze, astound

See also: astonishingly, astonishment, impressive, surprising

Type of: surprise

Encyclopedia: Astonish