obtuse

This word carries a heavy sense of frustration when applied to people. It does not describe a natural lack of intelligence, but rather a stubborn refusal to perceive the obvious or a willful blindness to a point being made. It suggests a mental dullness that acts as a barrier to communication. In a technical sense, the word evokes a sense of openness and bluntness. While a sharp angle cuts or pierces, an obtuse angle spreads wide, creating a visual feeling of flatness or lack of precision.