>Digital data, in information theory and information systems, are discrete, discontinuous representations of information or works, as contrasted with continuous, or analog signals which behave in a continuous manner, or represent information using a continuous function.

http://en.wikipedia.org/wiki/Digital_data

Though I have to say in this specific context the definition specific to clocks/watches makes just as much sense:

>(of a clock or watch) showing the time by means of displayed digits rather than hands or a pointer