The best replacement for password is passphrase.

The best alternatives to password are rated as following:
★★★★★  passphrase
★★★  encryption
★★★  passcode
★★  pin
★★  pattern
★  key
★  public key authentication
★  password
★  secret
★  yahoo id
★  fingerprint
★  network key
★  keyboard-interactive authentication
★  enable secret
★  biometric
★  key authentication
★  secret cisco
★  security key
★  unknown username for
  security question
  encryption key
  survey
  wep key
  id
  power on password
  administrator password
  user password
  pattern android
  unlock apple id
  iphone password
  change password
  wpa
  apple password
  roboform
  itunes password
  windows-password

Your alternative for password is not listed? Suggest!
Speaking about password, one probably shouldn't forget about 7zip.

Other search terms related to password and their ratings are:
★★★★★ 7zip
★★★★ ssh
★★★★ winrar
★★★★ htaccess
★★ .htaccess
★ yahoo
★ scp
★ email
★ survey
★ command prompt
yahoo mail
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Google Trends

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password
passphrase
encryption