a. | 1. | Concealed or hidden out of the way. |
2. | Remote from apprehension; difficult to be comprehended or understood; recondite; |
Adj. | 1. | abstruse - difficult to penetrate; incomprehensible to one of ordinary understanding or knowledge; "the professor's lectures were so abstruse that students tended to avoid them"; "a deep metaphysical theory"; "some recondite problem in historiography" |