The Collaborative International Dictionary of English v.0.48:

Password \Pass"word`\, n.
   A word to be given before a person is allowed to pass; a
   watchword; a countersign. --Macaulay.
   [1913 Webster]

WordNet (r) 3.0 (2006):

password
    n 1: a secret word or phrase known only to a restricted group;
         "he forgot the password" [syn: password, watchword,
         word, parole, countersign]

The Free On-line Dictionary of Computing (30 December 2018):

password

    An arbitrary string of characters chosen by a user
   or system administrator and used to authenticate the user
   when he attempts to log on, in order to prevent unauthorised
   access to his account.

   A favourite activity among unimaginative computer nerds and
   crackers is writing programs which attempt to discover
   passwords by using lists of commonly chosen passwords such as
   people's names (spelled forward or backward).  It is
   recommended that to defeat such methods passwords use a
   mixture of upper and lower case letters or digits and avoid
   proper names and real words.  If you have trouble remembering
   random strings of characters, make up an acronym like
   "ihGr8trmP" ("I have great trouble remembering my password").

   (1994-10-27)