stupid vs stunned

stupid is a noun but stunned is not a noun.

Word	Noun	Adjective	Verb	Adverb
stupid	Yes	Yes	No	No
stunned	No	Yes	No	No

As adjectives, stupid and stunned are synonyms defined as:

stupid and stunned: in a state of mental numbness especially as resulting from shock

Other synonyms of stupid include dazed, stupefied.

stupid (noun)	stunned (noun)
a person who is not very bright

stupid (adjective)	stunned (adjective)
lacking or marked by lack of intellectual acuity	in a state of mental numbness especially as resulting from shock
lacking intelligence	filled with the emotional impact of overwhelming surprise or shock
in a state of mental numbness especially as resulting from shock	knocked unconscious by a heavy blow