unascertainable vs unsearchable

unascertainable

adj
  • That cannot be ascertained; uncertain, unable to be determined or discovered. 

unsearchable

adj
  • That cannot be investigated or searched into; unknowable, inscrutable. 

  • Not capable of being searched; on which one cannot perform a search. 

  • That cannot be sought out or looked for. 

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