The Collaborative International Dictionary of English v.0.48:
Astonishing \As*ton"ish*ing\, a. Very wonderful; of a nature to excite astonishment; as, an astonishing event. [1913 Webster] Syn: Amazing; surprising; wonderful; marvelous. [1913 Webster] As*ton"ish*ing*ly, adv. -- As*ton"ish*ing*ness, n. [1913 Webster]