Mysterious
WordNet
adjective
(1) 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"
(2) 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"