inscrutable

Adjective

• 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
    

Related words

• Synonyms: 
  cryptic , cryptical , deep , mysterious , mystifying