arcane
adjective formal uk/ɑːˈkeɪn/ us/ɑːrˈkeɪn/
神秘的;秘密的;晦涩难解的
mysterious and known only by a few people
He was the only person who understood all the arcane details of the agreement. 他是唯一能看懂协议中所有那些晦涩难解的繁缛条文的人。
This argument may seem arcane to those not closely involved in the world of finance. 对于那些不谙金融界事务的人而言，这种观点如同天书。