A string of characters (letters, numbers, and other symbols) used to authenticate an identity or to verify access authorization.
Sources:
NIST SP 800-12 Rev. 1 under Password from FIPS 140-2

  A protected/private string of letters, numbers, and/or special characters used to authenticate an identity or to authorize access to data.
Sources:
CNSSI 4009-2015 from NSA/CSS Manual Number 3-16 (COMSEC)

  See memorized secret.
Sources:
NIST SP 800-63-3 under Password

  A string of characters (letters, numbers and other symbols) that is used to authenticate an identity, to verify access authorization or to derive cryptographic keys.
Sources:
NIST SP 800-57 Part 2 Rev.1 under Password

  A string of characters (letters, numbers and other symbols) that are used to authenticate an identity, verify access authorization or derive cryptographic keys.
Sources:
NIST SP 800-57 Part 1 Rev. 5 under Password

  A string of characters (letters, numbers, and other symbols) that are used to authenticate an identity or to verify access authorization. A passphrase is a special case of a password that is a sequence of words or other text. In this Recommendation, the use of the term “password” includes this special case.
Sources:
NIST SP 800-133 Rev. 2 under Password

  A string of characters (letters, numbers, and other symbols) used to authenticate an identity or to verify access authorization.
Sources:
NIST SP 800-82r3 from FIPS 140-2

  Confidential authentication information, usually composed of a string of characters.
Sources:
NISTIR 5153 under Password from ISO DIS 10181-2

  A string of characters (letters, numbers and other symbols) that are used to authenticate an identity, to verify access authorization or to derive cryptographic keys.
Sources:
NISTIR 7621 Rev. 1 under Password