Passphrase
A string of words used as a secret. Longer beats clever. Unique beats reused.
A passphrase is a sequence of words used to prove identity. Length and uniqueness do the work. Substituting @ for a does not.
Use a password manager to mint and store them. Share none. Change them when a service is breached, not on a 30-day ritual that trains people to increment a digit.
Fact source: ASD's ACSC glossary.