backwash vs swab

backwash

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

  • To affect with backwash. 

  • To clean the oil from wool after combing. 

noun
  • 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. 

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

swab

verb
  • To use a swab on something, or clean something with a swab. 

noun
  • A sailor; a swabby. 

  • A naval officer's epaulet. 

  • A small piece of soft, absorbent material, such as gauze, used to clean wounds, apply medicine, or take samples of body fluids. Often attached to a stick or wire to aid access. 

  • A mop, especially on a ship. 

  • A piece of material used for cleaning or sampling other items like musical instruments or guns. 

  • A sample taken with a swab (piece of absorbent material). 

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