The Oxford Thesaurus An A-Z Dictionary of Synonyms - obtuseadj.

1) rounded, unpointed, blunt: When mature, the leaves become more obtuse. 2) dull, insensitive, unfeeling, imperceptive, thick-skinned, stolid, thick, dense, doltish, cloddish, thickheaded, dull-witted, dim-witted, slow-witted, (mentally) retarded, boneheaded, lumpish, loutish, oafish, simple, simple-minded: Luke is a bit too obtuse to get the point of the story.