mothball vs take a rain check

mothball

verb
  • To store or shelve something no longer used. 

  • To stop using (something), but keep it in good condition. 

noun
  • A small ball of chemical pesticide (typically naphthalene) and deodorant placed in or around clothing and other articles susceptible to damage from mold or moth larvae in order to protect them from this damage. 

take a rain check

verb
  • To request or accept a rain check (an agreement from a merchant to honor a special offer, temporarily unavailable, after the expiration date). 

  • In social interactions, to request a deferral of an invitation. To "take a rain check" is a polite way to turn down an engagement, usually with the implication that one is simply postponing it and another time might be acceptable. 

How often have the words mothball and take a rain check occurred in a corpus of books? (source: Google Ngram Viewer )