(formal, disapproving) slow or unwilling to understand something (Oxford)
[usually before noun] (geometry) (of an angle) between 90° and 180° (Oxford)
stupid and slow to understand, or unwilling to try to understand (Cambridge)
Are you being deliberately obtuse? (Oxford)
He was either completely ignorant or being wilfully obtuse. (Oxford)
I’m not trying to be obtuse, but I don’t get it. (Cambridge)
being deliberately obtuse
being wilfully obtuse
trying to be obtuse
Dumb
Imperceptive
Intelligent
Sharp
Obtuseness