central vs protrusive

central

adj
  • Having or containing the centre of something. 

  • Being in the centre. 

  • Exerting its action towards the peripheral organs. 

  • Being very important, or key to something. 

noun
  • centre 

protrusive

adj
  • that protrudes; protruding 

  • rather conspicuous; obtrusive 

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