a priori vs ironclad

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. 

ironclad

adj
  • Solid or certain; not able to be disputed or questioned; irrefutable. 

  • Covered with iron, steel, or some metal; armor-plated. 

  • Rigorous; severe; exacting. 

  • Stubborn; inflexible. 

noun
  • An armor-plated warship, (especially) one preceding the invention of harveyized steel. 

  • A metal-plated ship, vessel, or vehicle. 

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