reflux vs relapse

reflux

verb
  • To flow back or return. 

  • To boil a liquid in a vessel having a reflux condenser 

noun
  • A technique, using a reflux condenser, allowing one to boil the contents of a vessel over an extended period. 

  • The backwards flow of any fluid. 

  • The leaking of stomach acid up into the oesophagus. 

relapse

verb
  • To slip or slide back physically; to turn back. 

  • To fall back again; to slide or turn back into a former state or practice. 

  • To return to a vice, especially self-harm or alcoholism, failing to maintain abstinence. 

  • To recur; to worsen, be aggravated (after a period of improvement). 

noun
  • An occasion when a person becomes ill again after a period of improvement 

  • The act or situation of relapsing. 

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