False Rejection Rate (FRR)

The probability that a biometric system will fail to identify an applicant, or verify the legitimate claimed identity of an applicant.
SOURCE: SP 800-76

The measure of the likelihood that the biometric security system will incorrectly reject an access attempt by an authorized user. A system’s false rejection rate typically is stated as the ratio of the number of false rejections divided by the number of identification attempts.
SOURCE: CNSSI-4009