invalid vs substantial

invalid

adj
  • Not valid; not true, correct, acceptable or appropriate. 

  • Suffering from disability or illness. 

  • Intended for use by an invalid. 

verb
  • To make invalid or affect with disease. 

  • To exempt from (often military) duty because of injury or ill health. 

substantial

noun
  • Anything having substance; an essential part. 

adj
  • Most important; essential. 

  • Not imaginary; real; actual; true; veritable. 

  • Having a substance; actually existing. 

  • Corporeal; material; firm. 

  • Possessed of goods or an estate; moderately wealthy. 

  • Satisfying; having sufficient substance to be nourishing or filling. 

  • Large in size, quantity, or value; ample; significant. 

  • Having good substance; strong; stout; solid; firm. 

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