1.（尤指故作）深奥的，难解的 You can describe something as abstruse if you find it difficult to understand, especially when you think it could be explained more simply.
英英释义
1.difficult to penetrate incomprehensible to one of ordinary understanding or knowledge
e.g. the professor's lectures were so abstruse that students tended to avoid them a deep metaphysical theory some recondite problem in historiography
