What does the word password mean?

Usage examples for password

  1. They reached the Khyber famished and were fed at Ali Masjid Fort, after King had given a certain password and had whispered to the officer commanding. – King--of the Khyber Rifles by Talbot Mundy
  2. It was all very simple, and, but for the one word, silent; but it was the first time I had heard a password, and it made an immense impression on my mind. – A Surgeon in Belgium by Henry Sessions Souttar
  3. What password best fitted that description? – Underground by Suelette Dreyfus