chaffer vs exchange of contracts

chaffer

noun
  • bargaining; merchandise 

  • The upper sieve of a cleaning shoe in a combine harvester, where chaff is removed 

verb
  • To talk much and idly; to chatter. 

  • To buy. 

  • To haggle or barter. 

exchange of contracts

noun
  • The act of exchanging contracts. 

  • The point or stage at which a conveyancing contract comes into existence between negotiating parties for the carrying out of a disposition of an estate in land; usually requiring the payment of a deposit. 

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