password

n. keyword, code word, special code that is used to gain entry (to a computer system, etc.)

A password is a form of secret authentication data that is used to control access to a resource. The password is kept secret from those not allowed access, and those wishing to gain access are tested on whether or not they know the password and are granted or denied access accordingly.The use of passwords goes back to ancient times. Sentries guarding a location would challenge for a password. They would only allow a person in if they knew the password. In modern times, passwords are used to control access to protected computer operating systems, mobile phones, cable TV decoders, automated teller machines (ATMs), etc. A typical computer user may require passwords for many purposes: logging in to computer accounts, retrieving email from servers, accessing files, databases, networks, web sites, and even reading the morning newspaper online.
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Noun
1. a secret word or phrase known only to a restricted group; "he forgot the password"
(synonym) watchword, word, parole, countersign
(hypernym) positive identification

n. password, keyword, code word

(n.)
A word to be given before a person is allowed to pass; a watchword; a countersign.