WordNet (r) 3.0 (2006):

application program
    n 1: a program that gives a computer instructions that provide
         the user with tools to accomplish a task; "he has tried
         several different word processing applications" [syn:
         application, application program, applications
         programme]

The Free On-line Dictionary of Computing (30 December 2018):

application program
app
application software
applications software

    (Or "application", "app") A
   complete, self-contained program that performs a specific
   function directly for the user.  This is in contrast to
   system software such as the operating system kernel,
   server processes, libraries which exists to support
   application programs and utility programs.

   Editors for various kinds of documents, spreadsheets, and
   text formatters are common examples of applications.  Network
   applications include clients such as those for FTP,
   electronic mail, telnet and WWW.

   The term is used fairly loosely, for instance, some might say
   that a client and server together form a distributed
   application, others might argue that editors and compilers
   were not applications but utility programs for building
   applications.

   One distinction between an application program and the
   operating system is that applications always run in user
   mode (or "non-privileged mode"), while operating systems and
   related utilities may run in supervisor mode (or "privileged
   mode").

   The term may also be used to distinguish programs which
   communicate via a graphical user interface from those which
   are executed from the command line.

   (2007-02-02)