Orphan Account
An account with no corresponding identity in the master record — typically left behind when someone departs and their access was never removed.
Regulators generally require organizations to actively detect and remove orphan accounts, because each one is standing access nobody is accountable for. They show up in every flavor of identity program — a dormant login at a hospital, an un-SSO’d growth tool at a startup, a federated guest account a consultancy never revoked.