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