a priori vs underivable

a priori

adv
  • In a way based on theoretical deduction rather than empirical observation. 

adj
  • Presumed without analysis. 

  • Self-evident, intuitively obvious. 

  • Based on hypothesis and theory rather than experiment or empirical evidence. 

  • Developed entirely from scratch, without deriving it from existing languages. 

underivable

adj
  • That cannot be derived. 

noun
  • Something that cannot be derived. 

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