WordNet (r) 3.0 (2006):

device driver
    n 1: (computer science) a program that determines how a computer
         will communicate with a peripheral device [syn: driver,
         device driver]

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

device driver

    Software to control a hardware component
   or peripheral device of a computer such as a magnetic
   disk, magnetic tape or printer.

   A device driver is responsible for accessing the hardware
   registers of the device and often includes an interrupt
   handler to service interrupts generated by the device.

   Device drivers often form part of the lowest level of the
   operating system kernel, with which they are linked when
   the kernel is built.  Some more recent systems have loadable
   device drivers which can be installed from files after the
   operating system is running.

   (1994-10-27)