the GNU version of the Collaborative International Dictionary of English
v. To strike dumb; to confuse with astonishment.
The Century Dictionary and Cyclopedia
To strike dumb; confuse; stupefy; confound.
Word Usage
"For him it was no new conviction that his presence in any part of the world, from Africa to the steppes of Muscovy alike, was enough to dumfound people and impel them to insane self-oblivion."