Dumbfound is defined as to amaze someone, or to make someone speechless because of shock.verb
If you say something so smart no one can believe it came out of your mouth and everyone is amazed, this is an example of when you dumbfound them.YourDictionary definition and usage example. Copyright © 2013 by LoveToKnow Corp.
Origin: dumb + (con)found
Used by arrangement with John Wiley & Sons, Inc.
also dum·foundtransitive verb dumb·found·ed also dum·found·ed, dumb·found·ing also dum·found·ing, dumb·founds also dum·founds
Origin: dumb + (con)found.