castoff vs negation

castoff

noun
  • Something that has been rejected or discarded; a reject. 

adj
  • discarded, rejected. 

negation

noun
  • A denial or contradiction. 

  • A proposition which is the contradictory of another proposition and which can be obtained from that other proposition by the appropriately placed addition/insertion of the word "not". (Or, in symbolic logic, by prepending that proposition with the symbol for the logical operator "not".) 

  • The logical operation which obtains such (negated) propositions. 

  • The act of negating something. 

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