the GNU version of the Collaborative International Dictionary of English
adj. causing astonishment.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
adj. bewildering or striking dumb with wonder
Word Usage
"Allison also accuses the Bush administration of "dumbfounding" passivity in response to North Korea's weapons program, which experts identified as "a greater potential threat than Iraq" in the days after 9/11."