A comprehensive assessment of the management, operational, and technical security controls in an information system, made in support of security accreditation, to determine the extent to which the controls are implemented correctly, operating as intended, and producing the desired outcome with respect to meeting the security requirements for the system.
Sources:
FIPS 200 under CERTIFICATION
NIST SP 800-18 Rev. 1 under Certification
NIST SP 800-60 Vol. 1 Rev. 1 under Certification from FIPS 200
NIST SP 800-60 Vol. 2 Rev. 1 under Certification from FIPS 200

  The process of verifying the correctness of a statement or claim and issuing a certificate as to its correctness.
Sources:
FIPS 201-3 under Certification

  Comprehensive evaluation of an information system component that establishes the extent to which a particular design and implementation meets a set of specified security requirements.
Sources:
CNSSI 4009-2015

  a formal process for testing components or systems against a specified set ofsecurity requirements. Certification is normally performed by an independent reviewer rather than one involved in building the system. Certification can be part of the review of security controls identified in OMB Circular A-130, Appendix III, which calls for security reviews to assure that management, operational, and technical controls are appropriate and functioning effectively. (See Accreditation.)
Sources:
NIST SP 800-16 under Certification

  Third-party attestation related to an object of conformity assessment, with the exception of accreditation.
Sources:
Cybersecurity Labeling for Consumer IoT Products under Certification