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

command interpreter
command-line interpreter

    A program which reads textual commands from
   the user or from a file and executes them.  Some commands may
   be executed directly within the interpreter itself
   (e.g. setting variables or control constructs), others may
   cause it to load and execute other files.

   Unix's command interpreters are known as shells.

   When an IBM PC is booted BIOS loads and runs the
   MS-DOS command interpreter into memory from file COMMAND.COM
   found on a floppy disk or hard disk drive.  The commands
   that COMMAND.COM recognizes (e.g. COPY, DIR, PRN) are called
   internal commands, in contrast to external commands which are
   executable files.

   (1995-03-16)