verb
(transitive, astronomy) To cover or hide from view.
(transitive, rare) To dissimulate, conceal, or obfuscate.
adjective
(medicine) Secret; hidden from general knowledge; undetected.
(medicine): not visible, but chemically detectable.
Related to the occult; pertaining to mysticism, magic, or astrology.
Esoteric.
noun
(usually with "the") Supernatural affairs.