An application, other than a major application, that requires attention to security due to the risk and magnitude of harm resulting from the loss, misuse, or unauthorized access to or modification of the information in the application. Minor applications are typically included as part of a general support system.
Sources:
CNSSI 4009-2015
from
NIST SP 800-18 Rev. 1
NIST SP 800-18 Rev. 1
under Minor Application