unfamiliar vs unplumbed

unfamiliar

adj
  • Strange, not familiar. 

noun
  • An unfamiliar person; a stranger. 

unplumbed

adj
  • Not measured for depth, with or as if with a plumb. 

  • Not assayed or measured in any way. 

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