Software program that performs a specific function directly for a user and can be executed without access to system control, monitoring, or administrative privileges.
NIST SP 800-16
The system, functional area, or problem to which information technology is applied. The application includes related manual procedures as well as automated procedures. Payroll, accounting, and management information systems are examples of applications.
NIST SP 800-37
NIST SP 800-40
Any data entry, update, query, or report program that processes data for the user.