a priori vs imponderable

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. 

imponderable

adj
  • Not ponderable; without sensible or appreciable weight; incapable of being weighed. 

  • Difficult or impossible to comprehend or evaluate. 

noun
  • An imponderable question. 

  • A factor that cannot be anticipated. 

  • An imponderable substance or body; specifically, in the plural, a name formerly applied to heat, light, electricity, and magnetism. 

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