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umlaut (o͝omˈlout) [Ger.,=transformed sound], in inflection, variation of vowels of the type of English man to men. In this instance it is the end product of the effect of a y (long since disappeared) that was present in the plural; the y caused the vowel before the n to be pronounced higher and more forward in the mouth in the plural than in the singular; eventually there was replacement of the vowel in the plural. Other examples are mouse, mice; tooth, teeth; to fall, to fell; doom, deem. Umlaut is also called mutation and inflection. For the variation of sing, sang, see ablaut. Umlaut is also the name for the diacritical symbol placed above a vowel to indicate a sound change in Germanic languages, as in the German Fräulein and the Swedish fröken (see accent).
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a phonetic change in the timbre of the vowels a, o, and u under the influence of the vowel i in the following syllable. In the Germanic languages, this change is influenced by certain other vowels in the following syllable as well. The term “umlaut” was introduced by J. Grimm.

The umlaut is a regressive assimilation of vowels. The conditioned variants occurring as a result of the umlaut may become independent phonemes, and their alternation (the grammatical umlaut) may become a morphological feature. For example, in modern German the umlaut is often a grammatical means for forming the plural of nouns, both when the environment determining the conditioned variant is absent and in many analogous forms, as in Gast-Gäste and Mutter-Mütter.


Steblin-Kamenskii, M. I. “Chto takoe ‘umlaut’?” In Materialy pervoi nauchnoi sessii po voprosam germanskogo iazykoznaniia. Moscow, 1959. Pages 52–63.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.