arcane

adj

1. Understood by only a few.

   “arcane rituals”

   “arcane knowledge”

   “The professor’s lecture was full of arcane references.”

   “The manuscript contained arcane symbols no one could decipher.”

   “He had an arcane knowledge of ancient rituals.”

2. (broadly)Obscure, mysterious.

   “arcane origins”

   “arcane details”

3. Requiring secret or mysterious knowledge to understand.

   “1997: Chris Horrocks, Introducing Foucault, page 67, The Renaissance Episteme (Totem Books, Icon Books; →ISBN A “signature” was placed on all things by God to indicate their affinities — but it was hidden, hence the search for arcane knowledge. Knowing was guessing and interpreting, not observing or demonstrating.”

4. Extremely old (e.g. interpretation or knowledge), and possibly irrelevant.

   “an arcane law”