obtuse

adjective

1. 1

   slow to learn or understand; lacking intellectual acuity

   so dense he never understands anything I say to him

   never met anyone quite so dim

2. 2

   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

3. 3

   of an angle; between 90 and 180 degrees

4. 4

   (of a leaf shape) rounded at the apex