Arcane

Arcane is a slang term used to describe something that is mysterious, secret, or difficult to understand. It is often associated with knowledge or information that is obscure or known only by a select few.

Example 1: “The professor’s lecture on quantum physics was so arcane that most of the students had a hard time comprehending it.”

Example 2: “She possesses an arcane skill of deciphering ancient hieroglyphics that no one else can understand.”