Arcane (adjective)

1. Known or understood by only a few people, typically those with specialist knowledge.
2. Mysterious or known only by a select few.

Origin:

From the latin word arcanus meaning "secret, hidden".

Examples:

1. The arcane ritual was performed only by the priests.
2. The word "arcane" comes from the Latin word arcanus meaning "secret, hidden".
3. His knowledge of arcane subjects was impressive.
4. The arcane symbols on the ancient text were difficult to decipher.
5. The arcane laws of the medieval kingdom were known only to the ruling elite.