negotiable vs usable

negotiable

adj
  • Able to be traversed; navigable. 

  • Able to be transferred to another person, with or without endorsement, in exchange for money. 

  • Open to negotiation or bargaining. 

noun
  • Something that is open to negotiation. 

usable

adj
  • Capable of being used. 

  • Easy to use; exhibiting good usability. 

  • homosexual 

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