In linguistics, the term ablaut (from German ab- in the sense "down, reducing" + Laut "sound") designates a system of vowel gradations in Proto-Indo-European and its far-reaching consequences in all of the modern Indo-European languages. The term "ablaut" was coined by the linguist Jacob Grimm, though the phenomenon was first described a century earlier by the Dutch linguist Lambert ten Kate in his book Gemeenschap tussen de Gottische spraeke en de Nederduytsche (1710). Ablaut can also be called apophony, vowel gradation, or vowel alternation.

Ablaut must be clearly distinguished from the later and unrelated phenomenon of umlaut (the fronting of vowels caused by a front vowel in a following syllable).


Ablaut in Proto-Indo-European

Proto-Indo-European had a characteristic general ablaut sequence that contrasted the vowel phonemes e/ē/o/ō/ø through the same root. The historical development in pre-Indo-European will presumably have been that the original e-grade, which could be long or short, underwent two changes in certain phonological environments: under certain circumstandes it changed its colouring to a (long or short) o (the o-grade), and in others it disappeared entirely (the zero-grade). Originally these five grades of ablaut will have born a purely allophonic relationship to each other, but later they came to carry meaning, distinguishing both lexis and grammatical form. The phonological conditions which controlled ablaut have been partly but not entirely explained; a key factor was the position of the word stress. Note that when we refer simply to the e-grade or o-grade, we mean the short vowel forms, unless the lengthened grades are specified. The e-grade is sometimes called the full grade. A classic example of the five grades of ablaut in a single root is provided by the different case forms of two closely related Greek words:

Ablaut grade PIE (reconstruction) Greek (Greek transcribed) Translation
e-grade or full grade *ph2-ter-om πα-τερ pa ter a "father" (noun, accusative)
lengthened e-grade *ph2-tēr πα-τηρ pa tēr "father" (noun, nominative)
zero-grade *ph2-tr-os πα-τρ-οσ pa tr os "father's" (noun, genitive)
o-grade *on-ph2-tor-om α-πα-τορ a pa tor a "fatherless" (adjective, accusative)
lengthened o-grade *on-ph2-tōr α-πα-τωρ a pa tōr "fatherless" (adjective, nominative)

[NB In this provisional transcription, om and on should be the letters m and n with a circle underneath them, to represent the syllabic sonorants of PIE. It would be good if someone can replace these with the correct symbols, and also add the accents and breathings on the Greek.]

We are interested here in the syllable in bold print. Crucial is also to notice which syllable carries the word stress - that in italics. In this untypically neat example, we see a switch to the zero-grade when the word stress moves to the following syllable, a switch to the o-grade when the word stress moves to the preceding syllable, and a lengthening of the vowel when there is no inflection.

The zero grade

The zero grade of ablaut is the one which causes most people the greatest difficulty. In the case of *ph2trós, which may already in PIE have been pronounced something like /patrós/, it is not difficult to imagine this as a contraction of an older *ph2terós, pronounced perhaps /paterós/, as this combination of consonants and vowels would be possible in English too. In other cases, however, the absence of a vowel strikes the speaker of a modern western European language as unpronounceable.

To understand this, one must be aware that PIE had a number of sounds which in principle were consonants, yet could operate in ways analogous to vowels. We are thinking here of the four syllabic sonorants, the three laryngeals and the two semi-vowels.

The syllabic sonorants are m, n, r and l, which could be consonants much as they are in English, but could also be held on as continuants and carry a full syllable stress. Compare r and l in the modern Slavic languages, or m and n in some African languages: in Srb, the Serbian word for "Serb", the r carries much the function of a vowel; in the African word Ngazija, the name of a Bantu language, the initial N- should be pronounced with a pulse, as a full syllable, without the help of a vowel.

The laryngeals could be pronounced as consonants, in which case they were probably variations on the h sound, hence we normally transcribe them h1, h2 and h3. However they could also carry a syllable stress, in which case they were more like vowels, hence some linguists prefer to transcribe them ə1, ə2 and ə3.

The phonemes u and i could be semi-vowels, probably pronouced like English w and y, or they could be pure vowels.

Thus any of these could replace the ablaut vowel when it was reduced to the zero-grade: the pattern CVrC (eg. *bhergh-) could become CrC (*bhrgh-).

When the ablaut vowel was followed by i or u, the result was a diphthong. Ablaut is nevertheless regular, and looks like this:

e-grade o-grade zero-grade
ei oi i
eu ou u

However, not every PIE syllable was capable of forming a zero grade; some consonant structures inhibited it in particular cases, or completely. So for example, although the preterite plural of a Germanic strong verb (see below) is derived from the zero grade, classes 4 and 5 have instead vowels representing the lengthened e-grade, as the stems of these verbs could not have sustained a zero grade in this position.

The a-grade

It is still a matter of debate whether PIE had an original a-vowel at all. In later PIE, the disappearance of the laryngeal h2 could leave an a-colouring and this may explain all occurrences of a in later PIE. However some argue that the e-grade could sometimes be replaced by an a-grade without the influence of a laryngeal. This is controversial, but might help to explain the vowels in class 6 Germanic verbs, for example.

Subsequent development of Ablaut

Although PIE only had this one, basically regular ablaut sequence, the development in the daughter languages is frequently far more complicated, and few reflect the original system as neatly as Greek. Various factors such as vowel harmony, assimilation with nasals, or the effect of the presence of laryngeals in the Indo-European roots and their subsequent loss in most daughter languages, mean that a language may have several different vowels representing a single vowel in the parent language. Thus while ablaut survives in some form in all Indo-European languages, it becomes progressively less systematic over time. In Germanic, for example, there are several parallel (but still regular) ablaut sequences and in modern English the vowel alterations appear to be entirely irregular.

Ablaut explains vowel differences between related words of the same language. For example:

  • English fetch and foot both come from the same IE root *ped-, the common idea being "going". The former comes from the e-grade, the latter from the lengthened o-grade.
  • German Berg (hill) and Burg (castle) both come from the root *bhergh-, which presumably meant "high". The former comes from the e-grade, the latter from the zero-grade. (Zero-grade followed by r becomes ur in Germanic.)

Ablaut also explains vowel differences between cognates in different languages.

  • English tooth comes from Germanic *tanţ-uz, which is obviously related to Latin dens, dentis and Greek οδουσ, οδοντοσ (same meaning), which we know in the English words dentist and orthodontic. The reconstructed IE root is identical to the Latin: *dent-. The consonant differences can be explained by regular sound shifts in primitive Germanic, but not the vowel differences: by the regular laws of sound changes, Germanic a goes back to PIE o. The explanation is that the Germanic and Greek words developed from the o-grade, the Latin word from the e-grade.
  • English foot, as we have seen, comes from the lengthened o-grade of *ped-. Greek πουσ, ποδοσ and Latin pes, pedis (cf. English octopus and pedestrian), come from the (short) o-grade and the e-grade respectively.

For the Engish-speaking non-specialist, the best reference work for quick information on IE roots, including the difference of ablaut grade behind related lexemes, is Calvert Watkins, The American Heritage dictionary of Indo-European Roots, 2nd edition, Boston & New York 2000.

(Note that in discussions of lexis, we normally cite IE roots in the e-grade and without any inflections.)

Ablaut and grammatical function

In PIE, there were already ablaut differences within the paradigms of verbs and nouns. These were not the main markers of grammatical form, since the inflection system served this purpose, but they must have been significant secondary markers.

As an example of ablaut in the paradigm of the noun in PIE, we might take pértus, from which we get the English words ford and (via Latin) port.

root (p-r) suffix (t-u)
Nominative *per-tu-s e-grade zero-grade
Accusative *per-tu-m e-grade zero-grade
Genitive *por-teu-s zero-grade e-grade
Dative *por-teu-ei zero-grade e-grade

An example in a verb: *bheidhonom "to wait" (cf. Scots "bide").

Infinitive *bheidh-ono-m e-grade
Perfect (3rd singular) *bhe-bhoidh-e o-grade (note reduplicating prefix)
Perfect (3rd plural) *bhe-bhidh-nt zero-grade (note reduplicating prefix)

In the daughter languages, these came to be important markers of grammatical distinctions. The vowel change in the Germanic strong verb, for example, is the direct descendent of that which we saw in the Indo-European verb paradigm. Examples in modern English are:

Infinitive Preterite Past participle
sing sang sung
give gave given
strive strove striven
dig dug dug

It was in this context of Germanic verbs that ablaut was first described, and this is still what most people primarily associate with the phenomenon. A fuller description of ablaut operating in English, German and Dutch verbs and of the historical factors governing these can be found at the article West Germanic strong verb.

The same phenomenon is displayed in the verb tables of Latin, Ancient Greek and Sanskrit. Examples of ablaut as a grammatical marker in Latin are the vowel changes in the perfect stem of verbs.

Present tense Perfect
ago egi "to do"
video vīdi "to see" (vowel lengthening)
sedeo sēdi "to sit" (vowel lengthening)
cado cecidi "to fall" (note reduplicating prefix)

Ablaut can often explain apparently random irregularities. For example, the verb "to be" in Latin has the forms est (he is) and sunt (they are). The equivalent forms in German are very similar: ist and sind. The difference between singular and plural in both languages is easily explained: the IE root is *es-. In the singular, the stem is stressed, so it remains in the e-grade, and it takes the inflection -t. In the plural, the inflection -nt is stressed, causing the stem to reduce to the zero grade: s-.

Related Topics

nl:ablaut id:Ablaut


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