arcane
adj. C1 Advanced US //ˌɑɹˈkeɪn// UK //ɑːkˈeɪn// ar·cane
adj. difficult to understand or know because it is very old, secret, or complex. You use this to describe things that feel like a mystery to most people.
adj. difficult to understand or know; relating to something secret, mysterious, or highly specialized. Often used to describe obscure knowledge or ancient traditions.
The old library contains many arcane texts.
The software's arcane coding made it nearly impossible for the new team to update the system.
The scholar spent years deciphering the arcane symbols found on the temple walls, hoping to unlock the secrets of the lost civilization.
Borrowed from Latin arcānus (“hidden, secret”), from arceō (“to shut up, enclose”); cognate with Latin arca (“a chest”).