central vs formational

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 

formational

adj
  • Of or pertaining to formation (in any of many contexts). 

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