incommensurable vs unique

incommensurable

noun
  • An incommensurable value or quantity; an irrational number. 

adj
  • Not able to be measured by the same standards as another term in the context. 

  • having a ratio that is not expressible as a fraction of two integers. 

  • having no common integer divisor except 1. 

unique

noun
  • A thing without a like; something unequalled or unparallelled; one of a kind. 

adj
  • Of a rare quality, unusual. 

  • Being the only one of its kind; unequaled, unparalleled or unmatched. 

  • Of a feature, such that only one holder has it. 

  • Particular, characteristic. 

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