invalid vs truthful

invalid

verb
  • To make invalid or affect with disease. 

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

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

  • Suffering from disability or illness. 

  • Intended for use by an invalid. 

truthful

adj
  • Honest, and always telling the truth. 

  • Accurately depicting what is real. 

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