further vs impair

further

verb
  • To encourage growth; to support progress or growth of something; to promote. 

  • To help forward; to assist. 

adv
  • To a greater extent or degree. 

  • Beyond what is already stated or is already the case. 

  • Also; in addition; furthermore; moreover. 

  • Following on (from). 

  • To, at or over a greater distance in space, time or other extent. 

adj
  • More distant; relatively distant. 

  • More, additional. 

impair

verb
  • To weaken; to affect negatively; to have a diminishing effect on. 

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