What does the word substitute mean?

Usage examples for substitute

  1. Sudden indisposition had prevented the palatine attending, but his grandson knew well how to be his substitute. – Thaddeus of Warsaw by Jane Porter
  2. Reading is nothing more than a substitute for thought of one's own. – The Art of Literature by Arthur Schopenhauer
  3. Insist on pure Methylen Blue, accept no substitute. – The Veterinarian by Chas. J. Korinek