backwash vs churning

backwash

noun
  • The result or consequence of an event; an aftermath. 

  • The saliva, spit or food particles that have flowed back into a drink after someone has drunk from it. 

  • The backward flow of water from oars or propeller or breaking waves. 

  • The situation where economic growth in one area harms other areas by attracting people and business away from those areas. 

  • The similar flow of air from an aircraft engine. 

verb
  • To affect with backwash. 

  • To clean the oil from wool after combing. 

  • To operate a water filter in the reverse direction in order to clean it. 

churning

noun
  • The act by which something is churned. 

  • The quantity of butter prepared (by churning) at one time. 

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