oracle

noun

• 1a priest or priestess acting as a medium through whom advice or prophecy was sought from the gods in classical antiquity.
• a place at which divine advice or prophecy was sought.
• a person or thing regarded as an infallible authority or guide on something:casting the attorney general as the oracle for and guardian of the public interest is simply impossible

• 2a response or message given by an oracle, typically one that is ambiguous or obscure.