Individual responsible for the installation and maintenance of an information system, providing effective information system utilization, adequate security parameters, and sound implementation of established Information Assurance policy and procedures.
Sources:
CNSSI 4009-2015
NIST SP 1800-16B under System Administrator from CNSSI 4009-2015
NIST SP 1800-16C under System Administrator from CNSSI 4009-2015
NIST SP 1800-16D under System Administrator from CNSSI 4009-2015

  An FCKMS role that is responsible for the personnel, daily operation, training, maintenance, and related management of an FCKMS other than its keys. The system administrator is responsible for initially verifying individual identities, and then establishing appropriate identifiers for all personnel involved in the operation and use of the FCKMS.
Sources:
NIST SP 800-152 under System administrator

  A person who manages a computer system, including its operating system and applications. A system administrator’s responsibilities are similar to that of a network administrator.
Sources:
NIST SP 800-44 Version 2 under System Administrator

  A person who manages a computer system, including its operating system and applications. Responsibilities are similar to that of a network administrator.
Sources:
NIST SP 800-45 Version 2 under System Administrator

  An individual, group, or organization responsible for setting up and maintaining a system or specific system elements, implements approved secure baseline configurations, incorporates secure configuration settings for IT products, and conducts/assists with configuration monitoring activities as needed.
Sources:
NIST SP 800-128 under system administrator

  Individual or group responsible for overseeing the day-to-day operability of a computer system or network. This position normally carries special privileges including access to the protection state and software of a system.
Sources:
NISTIR 4734 under System Administrator
NISTIR 7316 under System Administrator