incomprehensible

Adjective

• difficult to understand
  • the most incomprehensible thing about the universe is that it is comprehensible- A. Einstein
    

• incapable of being explained or accounted for
  • inexplicable errors
    
  • left the house at three in the morning for inexplicable reasons
    

Related words

• Synonyms: 
  uncomprehensible , inexplicable
• Antonyms: 
  comprehensible , comprehendible , explicable