obtuse

/əbˈtus/

/əbˈtus/

Other forms: obtuser; obtusest

The adjective obtuse is good for describing someone slow on the uptake: "Don't be so obtuse: get with the program!"

The adjective obtuse literally means "rounded" or "blunt," but when it's used for a person, it means "not quick or alert in perception" — in other words, not the sharpest tool in the shed. It's not just for dull people, but also dull angles: in geometry, an obtuse angle is one that is not so sharp (between 90 and 180 degrees).

Definitions of obtuse

1. adjective

   of an angle; between 90 and 180 degrees
   antonyms:

   acute

   of an angle; less than 90 degrees
2. adjective

   lacking in insight or discernment
   “too obtuse to grasp the implications of his behavior”

   synonyms: purblind

   undiscerning

   lacking discernment
3. adjective

   slow to learn or understand; lacking intellectual acuity
   “he was either normally stupid or being deliberately obtuse”

   synonyms: dense, dim, dull, dumb, slow

   stupid

   lacking or marked by lack of intellectual acuity
4. adjective

   (of a leaf shape) rounded at the apex
   synonyms:

   simple, unsubdivided

   (botany) of leaf shapes; of leaves having no divisions or subdivisions