Английский разговорный словарь (основной) - relativity

ˌreləˈtɪvɪtɪ n. 1 the fact or state of being relative. 2 Physics a (special theory of relativity) a theory based on the principle that all motion is relative and that light has constant velocity, regarding space-time as a four-dimensional continuum, and modifying previous conceptions of geometry. b (general theory of relativity) a theory extending this to gravitation and accelerated motion.