enigmatic vs unsolvable

enigmatic

adj

  • Pertaining to an enigma. 

  • Defying description. 

  • Mysterious. 

  • Enigmatical. 

unsolvable

adj

  • Not solvable. 

noun

  • A problem that cannot be solved. 

How often have the words enigmatic and unsolvable occurred in a corpus of books? (source: Google Ngram Viewer )