discard vs retain

discard

verb
  • To make a discard; to throw out a card. 

  • To throw away, to reject. 

  • To dismiss from employment, confidence, or favour; to discharge. 

noun
  • A temporary variable used to receive a value of no importance and unable to be read later. 

  • Anything discarded. 

  • A discarded playing card in a card game. 

retain

verb
  • To keep in possession or use. 

  • To employ by paying a retainer. 

  • To hold back (a pupil) instead of allowing them to advance to the next class or year. 

  • To keep in one's pay or service. 

  • To hold secure. 

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