Diachrony and synchrony

Synchrony and diachrony are two complementary viewpoints in linguistic analysis. A synchronic approach (from Ancient Greek: συν- "together" and χρόνος "time") 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, often the present. In contrast, a diachronic (from δια- "through" and χρόνος "time") approach, as in historical linguistics, considers the development and evolution of a language through history.

For example, the study of Middle English—when the subject is temporally limited to a sufficiently homogeneous form—is synchronic focusing on understanding how a given stage in the history of English functions as a whole. The diachronic approach, by contrast, studies language change by comparing the different stages. The terms synchrony and diachrony are often associated with historical linguist Ferdinand de Saussure, who considered the synchronic perspective as systematic but argued that language change is too unpredictable to be considered a system.