- Dumbfound is defined as to amaze someone, or to make someone speechless because of shock.
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.
This man appears to be dumbfounded.
dumbfound definition by Webster's New World
Origin: dumb plush (con)found
dumbfound definition by American Heritage Dictionary
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.