| general relativity | (n) a generalization of special relativity to include gravity (based on the principle of equivalence), Syn. Einstein's general theory of relativity, general theory of relativity, general relativity theory |
| relativity | (n) (physics) the theory that space and time are relative concepts rather than absolute concepts, Syn. relativity theory, theory of relativity, Einstein's theory of relativity |
| special relativity | (n) 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 theory, special theory of relativity, Einstein's special theory of relativity |