invalid vs worthless

invalid

adj
  • Intended for use by an invalid. 

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

  • Suffering from disability or illness. 

verb
  • To make invalid or affect with disease. 

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

worthless

adj
  • Having no worth or use; without value. 

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