A formal document that provides an overview of the security requirements for an information system and describes the security controls in place or planned for meeting those requirements.
Sources:
NIST SP 800-128
NIST SP 800-37 Rev. 2 from OMB Circular A-130 (2016)

  See System Security Plan.
Sources:
NIST SP 800-53 Rev. 5 under security plan
NIST SP 800-53A Rev. 5 under security plan

  See information system security plan.
Sources:
NIST SP 800-128 under system security plan
NIST SP 800-37 Rev. 2 under system security plan
NIST SP 800-37 Rev. 2 under security plan

  Formal document that provides an overview of the security requirements for an information system or an information security program and describes the security controls in place or planned for meeting those requirements. See system security plan or information security program plan.
Sources:
CNSSI 4009-2015 under security plan from NIST SP 800-18 Rev. 1

  A formal document that provides an overview of the security requirements for an information system or an information security program and describes the security controls in place or planned for meeting those requirements. The system security plan describes the system components that are included within the system, the environment in which the system operates, how the security requirements are implemented, and the relationships with or connections to other systems.
Sources:
NIST SP 800-53 Rev. 5 under security plan
NIST SP 800-53A Rev. 5 under security plan

  See security plan.
Sources:
NIST SP 800-53 Rev. 5 under system security plan
NIST SP 800-53A Rev. 5 under system security plan
NIST SP 800-53B under system security plan

  Formal document that provides an overview of the security requirements for an information system or an information security program and describes the security controls in place or planned for meeting those requirements. The system security plan describes the system components that are included within the system, the environment in which the system operates, how the security requirements are implemented, and the relationships with or connections to other systems.
Sources:
NIST SP 800-53B under security plan

  A document that describes how an organization meets the security requirements for a system or how an organization plans to meet the requirements. In particular, the system security plan describes the system boundary, the environment in which the system operates, how security requirements are implemented, and the relationships with or connections to other systems.
Sources:
NIST SP 800-172 under system security plan

  A document that describes how an organization meets or plans to meet the security requirements for a system. In particular, the system security plan describes the system boundary, the environment in which the system operates, how security requirements are implemented, and the relationships with or connections to other systems.
Sources:
NIST SP 800-172A under system security plan

  Formal document that provides an overview of the security requirements for an information system and describes the security controls in place or planned for meeting those requirements.
Sources:
NIST SP 800-82r3 under security plan from NIST SP 800-18 Rev. 1

  A document that describes how an organization meets the security requirements for a system or how an organization plans to meet the requirements. In particular, the system security plan describes the system boundary; the environment in which the system operates; how the security requirements are implemented; and the relationships with or connections to other systems.
Sources:
NIST SP 800-171 Rev. 2 under system security plan