rational vs unsound

rational

adj
  • Logically sound; not self-contradictory or otherwise absurd. 

  • Healthy or balanced intellectually; exhibiting reasonableness. 

  • Of an algebraic expression, capable of being expressed as the ratio of two polynomials. 

  • Expressing the type, structure, relations, and reactions of a compound; graphic; said of formulae. 

  • Of a number, capable of being expressed as the ratio of two integers. 

  • Expressing a physical object. 

  • Capable of reasoning. 

noun
  • A rational number: a number that can be expressed as the quotient of two integers. 

  • The breastplate worn by Israelite high priests. 

unsound

adj
  • Not good, unreliable. 

  • Not whole, not solid, defective. 

  • Infirm, diseased. 

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