- 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.
Origin of dumbfounddumb + (con)found
transitive verbdumb·found·ed, dumb·found·ing, dumb·founds also dum·found·ed or dum·found·ing or dum·founds
Origin of dumbfounddumb + (con)found.