“Seriously, it is you, pet, who needs a good dictionary; not to mention a good thesaurus.”
Um....I think you are incorrect. Here is what the Thesaurus states:
Main Entry: obtuse
Part of Speech: adjective
Definition: slow to understand
Synonyms: dense, dopey, dull*, dumb, imperceptive, insensitive, opaque, slow on uptake, stolid, thick, uncomprehending, unintelligent
Notes: acute is an angle of less than 90 degrees; obtuse is one of more than 90 degrees
Antonyms: bright, intelligent, quick, smart
* = informal/non-formal usage
If not, perhaps you should. :-)