diachronic (adj.)

One of the two main temporal dimensions of linguistic investigation introduced by Ferdinand de Saussure, the other being synchronic. In diachronic linguistics (sometimes called linguistic diachrony), languages are studied from the point of view of their historical development – for example, the changes which have taken place between Old and Modern English could be described in phonological, grammatical and semantic terms (‘diachronic phonology/ syntax/ semantics’). An alternative term is historical linguistics. The earlier study of language in historical terms, known as comparative philology, does not differ from diachronic linguistics in subject-matter, but in aims and method. More attention is paid in the latter to the use of synchronic description as a preliminary to historical study, and to the implications of historical work for linguistic theory in general.