thickheaded vs boneheaded

thickheaded and boneheaded both are adjectives.

Word	Noun	Adjective	Verb	Adverb
thickheaded	No	Yes	No	No
boneheaded	No	Yes	No	No

As adjectives, thickheaded and boneheaded are synonyms defined as:

Other synonyms of thickheaded include blockheaded, duncical, duncish, fatheaded, loggerheaded, thick-skulled, thick, wooden-headed.

thickheaded (adjective)	boneheaded (adjective)
(used informally) stupid	(used informally) stupid