Learn in the textbookAdvanced Authentication Methods and Payment Authentication
DefinitionPasswordless authentication (パスワードレス認証) confirms identity without asking for a password, using biometric data or a device you hold instead.
ExplanationPasswords can be guessed, spied on over someone's shoulder, or reused across other services. Passwordless authentication checks a body feature such as a fingerprint or face, or something you hold such as a registered smartphone or security key, so there is nothing to memorise and those password weaknesses disappear. Under the FIDO standard, for example, the fingerprint (or other biometric) match happens inside the user's own device, and the data used for matching never travels over the network.
AnalogyIt is like replacing a combination lock, where you must remember and key in a number, with a door that opens when you tap your registered staff badge or simply show your face.
Memory hookThe "-less" means "without", as in paperless or cashless; the Japanese name パスワードレス認証 borrows the same English suffix, so it reads as authentication without a password.