“Synchrony and diachrony are two different and complementary viewpoints in linguistic analysis. A synchronic approach considers a language at a moment in time without taking its history into account. Synchronic linguistics aims at describing a language at a specific point of time, usually the present.
Diachrony is the development or succession of events and processes over time. … As synchrony is the coincidence of facts, phenomena or processes in time and therefore two events, two processes or part of them are synchronous when there is a temporal correspondence between both.” IT’S A LIVING
