Etymology () is the study of the history of words. By extension, the term "the etymology (of a word)" means the origin of the particular word and for place names, there is a specific term, toponymy.
For Greek—with a long written history—etymologists make use of texts, and texts about the language, to gather knowledge about how words were used during earlier periods and when they entered the language. Etymologists also apply the methods of comparative linguistics to reconstruct information about languages that are too old for any direct information to be available.
By analyzing related languages with a technique known as the comparative method, linguists can make inferences about their shared parent language and its vocabulary. In this way, word roots have been found that can be traced all the way back to the origin of, for instance, the Indo-European language family.
Even though etymological research originally grew from the philological tradition, much current etymological research is done on language families where little or no early documentation is available, such as Uralic and Austronesian.
The word etymology derives from the Greek word ἐτυμολογία (etumología), itself from ἔτυμον (étumon), meaning "true sense", and the suffix -logia, denoting "the study of".In linguistics, the term etymon refers to a word or morpheme (e.g., stem or root) from which a later word derives. For example, the Latin word candidus, which means "white", is the etymon of English candid.
Philology is the study of language in oral and written historical sources; it is the intersection of textual criticism, literary criticism, history, and linguistics. Philology is more commonly defined as the study of literary texts as well as oral and written records, the establishment of their authenticity and their original form, and the determination of their meaning. A person who pursues this kind of study is known as a philologist.
In older usage, especially British, philology is more general, covering comparative and historical linguistics.Classical philology studies classical languages. Classical philology principally originated from the Library of Pergamum and the Library of Alexandria around the fourth century BCE, continued by Greeks and Romans throughout the Roman/Byzantine Empire. It was preserved and promoted during the Islamic Golden Age, and eventually resumed by European scholars of the Renaissance, where it was soon joined by philologies of other non-Asian (European) (Germanic, Celtic), Eurasian (Slavistics, etc.), Asian (Arabic, Persian, Sanskrit, Chinese, etc.), and African (Egyptian, Nubian, etc.) languages. Indo-European studies involves the comparative philology of all Indo-European languages.
Philology, with its focus on historical development (diachronic analysis), is contrasted with linguistics due to Ferdinand de Saussure's insistence on the importance of synchronic analysis. The contrast continued with the emergence of structuralism and Chomskyan linguistics alongside its emphasis on syntax, although research in the field of historical linguistics is often characterized by reliance on philological materials and findings.