acarpous vs unworkable

acarpous

adj
  • Not producing fruit; unfruitful; sterile. 

unworkable

adj
  • Not workable or operable; not practical; unmanageable. 

noun
  • Something that is not workable, or cannot be made to work. 

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