— absurd
— anserine
— asinine
— birdbrained
— blockheaded
— boneheaded
— brainless
— cloddish
— cockamamie
— cockamamy
— cockeyed
— confused
— dense
— derisory
— dim
— doltish
— dopey
— dopy
— dull
— dumb
— duncical
— duncish
— fatheaded
— fatuous
— fond
— foolish
— gaumless
— goofy
— gooselike
— goosey
— goosy
— gormless
— harebrained
— headless
— idiotic
— ill-advised
— ill-conceived
— impolitic
— imprudent
— inadvisable
— inane
— insane
— jerky
— laughable
— loggerheaded
— ludicrous
— lumpen
— lumpish
— mad
— mindless
— misbegotten
— misguided
— muttonheaded
— nitwitted
— nonsensical
— obtuse
— pea-brained
— preposterous
— rattlebrained
— rattlepated
— retarded
— ridic
— ridiculous
— sappy
— scatterbrained
— scatty
— senseless
— set foot in
— side of the face
— silly
— slow
— soft-witted
— staved off
— stop at
— stuffed
— stupid person
— stupidity
— thick
— thick-skulled
— thick-witted
— thickheaded
— unacademic
— unadvisable
— unadvised
— unthinking
— unwise
— vacuous
— wacky
— weak
— whacky
— witless
— wooden-headed
— yokel-like
— zany