A measure of the degree to which an organization depends on the information or information system for the success of a mission or of a business function.
Sources:
CNSSI 4009-2015 from NIST SP 800-60 Vol. 1 Rev. 1
NIST SP 800-30 Rev. 1 under Criticality
NIST SP 800-60 Vol. 1 Rev. 1 under Criticality
NIST SP 800-60 Vol. 2 Rev. 1 under Criticality

  Refers to the (consequences of) incorrect behavior of a system. The more serious the expected direct and indirect effects of incorrect behavior, the higher the criticality level.
Sources:
CNSSI 4009-2015 under criticality level

  An attribute assigned to an asset that reflects its relative importance or necessity in achieving or contributing to the achievement of stated goals.
Sources:
NIST SP 800-160 Vol. 2 Rev. 1

  Degree of impact that a requirement, module, error, fault, failure, or other item has on the development or operation of a system.
Sources:
NIST SP 800-160v1r1