WordNet (r) 3.0 (2006):

speed of light
    n 1: the speed at which light travels in a vacuum; the constancy
         and universality of the speed of light is recognized by
         defining it to be exactly 299,792,458 meters per second
         [syn: speed of light, light speed, c]

The Jargon File (version 4.4.7, 29 Dec 2003):

speed of light


    The absolutely fastest a particular algorithm or application could be
    implemented, given a set of constraints that are assumed to be
    unchangeable. For example, ?This would take 60 microseconds without any
    processing whatsoever, so that's the speed of light.? However, as one
    brilliant hacker once commented: ?Remember that the speed of light only is
    constant if you can't redesign the universe.?