Re: to be imparted by oral instruction...
1 annoyingly insensitive or slow to understand : he wondered if the doctor was being deliberately obtuse. See note at stupid .
• difficult to understand : some of the lyrics are a bit obtuse.
2 (of an angle) more than 90° and less than 180°.
• not sharp-pointed or sharp-edged; blunt.
difficult to understand; obscure : an abstruse philosophical inquiry. See note at obscure .
The friend the teacher,