leftover vs necessary

leftover

noun
  • Something left behind; an excess or remainder. 

  • Remaining after a meal is complete or eaten for a later meal or snack. 

adj
  • Remaining; left behind; extra; in reserve. 

necessary

adj
  • Unavoidable, inevitable. 

  • Required, essential, whether logically inescapable or needed in order to achieve a desired result or avoid some penalty. 

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