esoteric

他的文风刻意艰深，面向有限的受众。

His prose is deliberately ___esoteric, aimed at a narrow audience.

这位哲学家喜欢讨论一些深奥难懂的理论，普通人很难理解。

The philosopher enjoys discussing ___esoteric theories that are hard for ordinary people to grasp.

那本关于古代符号学的书太深奥了，只有少数专家能看懂。

The book on ancient semiotics was so ___esoteric that only a few experts could understand it.