spartan vs unbooked

spartan

adj
  • Lacking in decoration and luxury. 

  • Resolute in the face of danger or adversity. 

  • Austere, frugal, characterized by self-denial. 

unbooked

adj
  • Not booked. 

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