stupid vs dullard

stupid and dullard both are nouns.

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

As nouns, stupid and dullard are synonyms defined as:

Other synonyms of stupid include dolt, pillock, poor fish, pudden-head, pudding head, stupe, stupid person.

stupid (noun)	dullard (noun)
a person who is not very bright	a person who evokes boredom
	a person who is not very bright

stupid (adjective)	dullard (adjective)
lacking or marked by lack of intellectual acuity
lacking intelligence
in a state of mental numbness especially as resulting from shock