Synonyms and related words :
blunt, blunt-witted, dim, dopey, dull, dull of mind, dull-headed, dull-pated, dull-witted, fat-witted, gross-headed, heavy, hebetudinous, obtuse, slow, slow-witted, sluggish, thick-brained, thick-headed, thick-pated, thick-witted, thickskulled, wooden