unallowable vs untenable

unallowable

adj
  • Not allowable 

  • For which an allowance may not be claimed 

untenable

adj
  • Not able to be held, as of an opinion or position. 

  • Unfit for habitation. 

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