mysterious in WordNet English dictionary

1. 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"
   cryptic  cryptical  deep  inscrutable  mysterious  mystifying 
   
2. 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"
   mysterious  mystic  mystical  occult  secret  orphic