Synonyms for Boneheaded:

adj.

blockheaded (adjective)
thick-skulled, loggerheaded.
half-baked (adjective)
blockheaded.
ignorant (adjective)
thickheaded.
thick (adjective)
thickheaded.

n.

boneheaded (noun)
fatheaded, thick-skulled, thick, wooden-headed, thickheaded, loggerheaded, blockheaded.

Other synonyms:

Other relevant words:
blockheaded.