obtusity

/ɑbˈtusəti/
noun
  1. The quality of being slow to understand or perceive; dullness of mind.
    • The teacher was patient with the student's obtusity, offering extra help after class.
    • His obtusity during the meeting frustrated everyone who tried to explain the simple plan.
    • She couldn't hide her obtusity when she failed to grasp the joke after three explanations.
  2. The state of being blunt or not sharp; lack of sharpness in an object or angle.
    • The sculptor complained about the obtusity of his chisel, which wouldn't carve fine details.
    • In geometry class, we measured the obtusity of the angle at 120 degrees.
    • The obtusity of the old knife made it useless for cutting vegetables.