a priori vs blue-skies

a priori

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. 

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

blue-skies

adj
  • Unrealistic or impractical. 

  • Of no immediate practical application. 

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