n. 1. The main loop of an event-processing program; the code that gets commands and dispatches them for execution. 2. [techspeak] In `device driver', code designed to handle a particular peripheral device such as a magnetic disk or tape unit. 3. In the TeX world and the computerized typesetting world in general, `driver' also means a program that translates some device-independent or other common format to something a real device can actually understand.