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.