Obtuse

1. adjective

   slow to learn or understand; lacking intellectual acuity; ; ; - Thackeray

   “so dense he never understands anything I say to him”

   Similar: dense, dim, dull, dumb, slow

2. adjective

   lacking in insight or discernment; ; - Jasper Griffin

   “too obtuse to grasp the implications of his behavior”

   Similar: purblind

3. adjective

   of an angle; between 90 and 180 degrees

4. adjective

   (of a leaf shape) rounded at the apex