Indo-European ablaut

In linguistics, the Indo-European ablaut (/ˈæblaʊt/ AB-lowt, from German Ablaut pronounced [ˈaplaʊt]) is a system of apophony (regular vowel variations) in the Proto-Indo-European language (PIE).

An example of ablaut in English is the strong verb sing, sang, sung and its related noun song, a paradigm inherited directly from the Proto-Indo-European stage of the language. Traces of ablaut are found in all modern Indo-European languages, though its prevalence varies greatly.

The phenomenon of Indo-European ablaut was first recorded by Sanskrit grammarians in the later Vedic period (roughly 8th century BCE), and was codified by Pāṇini in his Aṣṭādhyāyī (4th century BCE), where the terms guṇa and vṛddhi were used to describe the phenomena now known respectively as the full grade and lengthened grade.

In the context of European languages, the phenomenon was first described in the early 18th century by the Dutch linguist Lambert ten Kate, in his book Gemeenschap tussen de Gottische spraeke en de Nederduytsche ("Common aspects of the Gothic and Dutch languages", 1710).

The term ablaut is borrowed from German, and derives from the noun Laut "sound", and the prefix ab-, which indicates movement downwards or away, or deviation from a norm; thus the literal meaning is "sound derivation". It was coined in this sense in 1819 by the German linguist Jacob Grimm in his Deutsche Grammatik, though the word had been used before him. In particular, the 17th-century grammarian Schottelius had used the word negatively to suggest that German verbs lacked the sophistication of the classics, but there is no hint of this disdain in Grimm or in modern scholarly usage.

In English, the term became established through the 1845 translation of Bopp's Comparative Grammar.

Vowel gradation is any vowel difference between two related words (such as photograph [ˈfoʊtəgrɑːf] and photography [fəˈtɒgrəfi]) or two forms of the same word (such as man and men). The difference does not need to be indicated in the spelling. There are many kinds of vowel gradation in English and other languages, which are discussed generally in the article apophony. Some involve a variation in vowel length (quantitative gradation: photograph / photography shows reduction of the first vowel to a schwa), others in vowel coloring (qualitative gradation: man / men) and others the complete disappearance of a vowel (reduction to zero: could not → couldn't).

For the study of European languages, one of the most important instances of vowel gradation is the Indo-European ablaut, remnants of which can be seen in the English verbs ride, rode, ridden, or fly, flew, flown. For simply learning English grammar, it is enough to note that these verbs are irregular, but understanding why they have unusual forms that seem irregular (and indeed why they are actually perfectly regular within their own terms) requires an understanding of the grammar of the reconstructed proto-language.