A friend of mine once described a mutual acquaintance in this way:
She can be obtuse.
The dictionary definition of "obtuse" seems to suggest a "lack of intellect or intelligence". However, this really seems to be unlikely to be what she meant, since it seems a very harsh way to speak about anyone. And also it does not describe the acquaintance whatsover, since she is a very smart woman.
The context of the sentence would seem to imply that it had something to do with stubbornness. Is that a possible interpretation?