A domain that implements a security policy and is administered by a single authority.
Sources:
CNSSI 4009-2015 from CNSSP 24, CNSSI 1253F Attachment 3
NIST SP 800-137 under Security Domain from CNSSI 4009
NIST SP 800-172 from CNSSI 4009-2015 - Adapted
NIST SP 800-172A from CNSSI 4009-2015 - Adapted
NIST SP 800-53 Rev. 5 from CNSSI 4009-2015
NIST SP 800-171 Rev. 2 from CNSSI 4009 - Adapted

  An environment or context that includes a set of system resources and a set of system entities that have the right to access the resources as defined by a common security policy, security model, or security architecture. See Security Domain.
Sources:
NIST SP 800-53 Rev. 5 under domain

  A system or subsystem that is under the authority of a single trusted authority. Security domains may be organized (e.g., hierarchically) to form larger domains.
Sources:
NIST SP 800-57 Part 1 Rev. 5 under Security domain

  An environment or context that includes a set of system resources and a set of system entities that have the right to access the resources as defined by a common security policy, security model, or security architecture.
Sources:
CNSSI 4009-2015 under domain

  A set of elements, data, resources, and functions that share a commonality in combinations of (1) roles supported, (2) rules governing their use, and (3) protection needs.
Sources:
NIST SP 800-160v1r1 under domain from ISO/IEC/IEEE 24765:2017

  Set of assets and resources subject to a common security policy.
Sources:
NIST SP 800-160v1r1 from ISO/IEC 19989-3:2020