mysterious

of an obscure nature

• “the new insurance policy is written without cryptic or mysterious terms”
• “a deep dark secret”
• “the inscrutable workings of Providence”
• “in its mysterious past it encompasses all the dim origins of life” Rachel Carson
• “rituals totally mystifying to visitors from other lands”

having an import not apparent to the senses nor obvious to the intelligence; beyond ordinary understanding

• “mysterious symbols”
• “the mystical style of Blake”
• “occult lore”
• “the secret learning of the ancients”