Quick Definition
False Rejection Rate, or FRR, is a measure of how often a biometric authentication system incorrectly rejects an authorized user.
Authentication systems should strive to have the lowest possible FRR in order to avoid interruptions in productivity and reduce user frustration and users' tendencies to seek workarounds to authentication flows. For these reasons, authentication systems that are so strict as to produce an elevated FRR can paradoxically be a net negative for information security.