invalid vs spurious

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. 

spurious

adj
  • False, not authentic, not genuine. 

  • Extraneous; stray; not relevant or wanted. 

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