dumfounded vs dumbfounded

dumfounded and dumbfounded both are adjectives.

Word	Noun	Adjective	Verb	Adverb
dumfounded	No	Yes	No	No
dumbfounded	No	Yes	No	No

As adjectives, dumfounded and dumbfounded are synonyms defined as:

dumfounded and dumbfounded: as if struck dumb with astonishment and surprise

Other synonyms of dumfounded include dumbstricken, dumbstruck, flabbergasted, stupefied, thunderstruck.

dumfounded (adjective)	dumbfounded (adjective)
as if struck dumb with astonishment and surprise	as if struck dumb with astonishment and surprise