False Acceptance

When a biometric system incorrectly identifies an individual or incorrectly verifies an impostor against a claimed identity
SOURCE: SP 800-76

In biometrics, the instance of a security system incorrectly verifying or identifying an unauthorized person. It typically is considered the most serious of biometric security errors as it gives unauthorized users access to systems that expressly are trying to keep them out.
SOURCE: CNSSI-4009