Synchronic linguistics deals with a language at a specific point in time; it is opposed to diachronic linguistics (also called historical linguistics), which deals with how languages change over time. Historical linguistics (also diachronic linguistics or comparative linguistics) is primarily the study of the ways in which languages change over time, by means of examining languages which are recognizably related through similarities such as vocabulary, word formation, and syntax, as well as the surviving records of ancient languages. ...

By extension, a synchronic process in a language is one that is exhibited at a specific time, as opposed to a process that occurs over time. For example, in English, there is a synchronic distinction between the pronouns he and she: both are used, with different meanings. By contrast, there is a diachronic distinction between the suffixes -eth and -s/-es: the suffix -eth was once used exclusively, and now -s/-es is used exclusively. (In the transitional period, both were used, and one might say that there was a synchronic distinction at the time.) The English language is a West Germanic language that originates in England. ...

The term synchronic also has uses outside of linguistics; for example, in modern philosophy of mind, it is employed to analyze the facilitation of immediate conscious awareness in relatively brief time scales (such as 100 milliseconds). Philosophy of mind is the philosophical study of the nature of the mind, mental events, mental functions, mental properties, and consciousness. ... Consciousness is a quality of the mind generally regarded to comprise qualities such as subjectivity, self-awareness, sentience, sapience, and the ability to perceive the relationship between oneself and ones environment. ...