WordNet (r) 3.0 (2006):

special relativity theory
    n 1: a physical theory of relativity based on the assumption
         that the speed of light in a vacuum is a constant and the
         assumption that the laws of physics are invariant in all
         inertial systems [syn: special relativity, special
         theory of relativity, special relativity theory,
         Einstein's special theory of relativity]