Recondite (adjective)

1. Obscure, difficult to understand, known by only a few.
2. Deeply hidden, not easily discovered.

Origin:

From latin reconditus "hidden, concealed," past participle of recondere "put away, store up," from re- "again" + condere "to store".

Examples:

1. The philosopher's recondite ideas were hard to grasp.
2. The poem's meaning was recondite and required careful study.
3. The scientist's theories were recondite and only understood by a select few.
4. The professor's lecture on recondite subjects was attended by a small group of students.
5. The recondite secrets of the ancient civilization were finally uncovered after years of research.