The definition of astound is to shock, surprise or amaze.(verb)
If you tell someone something that is totally amazing or confusing, this is an example of astound.
See astound in Webster's New World College Dictionary
Origin: < ME astouned, astoned, pp. of astonien, astonish
See astound in American Heritage Dictionary 4
transitive verb a·stound·ed, a·stound·ing, a·stounds
Origin: From Middle English astoned
Origin: , past participle of astonen, to amaze; see astonish.
Learn more about astound