What is the meaning of obtuse?

adjective

• Of an angle; between 90 and 180 degrees.
• Of a leaf shape. ( rounded at the apex)
• Lacking in insight or discernment."too obtuse to grasp the implications of his behavior"; "a purblind oligarchy that flatly refused to see that history was condemning it to the dustbin- Jasper Griffin
  • synonyms: purblind
• Slow to learn or understand; lacking intellectual acuity.
  • usage: "so dense he never understands anything I say to him"; "never met anyone quite so dim"; "although dull at classical learning, at mathematics he was uncommonly quick- Thackeray; "dumb officials make some really dumb decisions"; "he was either normally stupid or being deliberately obtuse"; "worked with the slow students"
  • synonyms: dense, dim, dull, dumb, slow