arcanely

The ancient text was arcanely written, using codes that had not been seen for centuries.

(Chinese) 这段古文写得极其晦涩，使用了几个世纪以来都未见过的代码。

The scientist explained his theory so arcanely that none of the students understood it.

(Chinese) 这位科学家对他的理论解释得如此深奥，以至于没有一个学生听得懂。