obtuse

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).

Primary Meanings of obtuse

1.
 adj
of an angle; between 90 and 180 degrees
2.
 adj
lacking in insight or discernment
3.
 adj
(of a leaf shape) rounded at the apex
Full Definitions of obtuse
1

adj of an angle; between 90 and 180 degrees

Antonyms:
acute
of an angle; less than 90 degrees
2

adj lacking in insight or discernment

“too obtuse to grasp the implications of his behavior”
Synonyms:
purblind
undiscerning
lacking discernment

adj 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
3

adj (of a leaf shape) rounded at the apex

Synonyms:
simple, unsubdivided
(botany) of leaf shapes; of leaves having no divisions or subdivisions

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