• WordNet 3.6
    • n umlaut a diacritical mark (two dots) placed over a vowel in German to indicate a change in sound
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Webster's Revised Unabridged Dictionary
    • n umlaut (Philol) The euphonic modification of a root vowel sound by the influence of au, or especially i, in the syllable which formerly followed.☞ It is peculiar to the Teutonic languages, and was common in Anglo-Saxon. In German the umlauted vowels resulting from a o u, followed by old i, are written ä ö ü, or ae oe ue; as, männer or maenner, men, from mann, man. Examples of forms resulting from umlaut in English are geese pl. of goose men pl. of man, etc.
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Century Dictionary and Cyclopedia
    • n umlaut In philology, the German name, invented by Grimm, for a vowel-change in the Germanic languages, brought about by the influence of a vowel in the succeeding syllable: namely, of the vowel i, modifying the preceding vowel in the direction of e or i, and of the vowel u, modifying the preceding vowel toward a or u. Only the former, or the change by a following i (now generally lost or altered), is found in English or German: thus, German mann, männer; fall, fällen; maus, mäuse; fuss, füsse; etc.; in English the phenomena are only sporadic remains, like man, men; fall, fell; mouse, mice; foot, feet. In Icelandic both kinds of umlaut are frequent and regular changes. An English name sometimes used for ‘umlaut’ is mutation. Compare ablaut.
    • umlaut In philology, to form with the umlaut, as a form; also, to affect or modify by umlaut, as a sound.
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Chambers's Twentieth Century Dictionary
    • n Umlaut ōōm′lowt Grimm's word for a vowel-change in the Teutonic languages brought about on a preceding vowel by the vowel i (or e) modifying the first in the direction of e or i—German gänse, the plural of gans, &c.
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Webster's Revised Unabridged Dictionary
G., from um, about + laut, sound


In literature:

Do you suppose it's the umlauts?
"Fanny Herself" by Edna Ferber
UMLAUT, name given by Grimm to the modification of a vowel in a syllable through the influence of a vowel in the succeeding.
"The Nuttall Encyclopaedia" by Edited by Rev. James Wood
There is no trace of such vocalic mutation ("umlaut") in Gothic, our most archaic Germanic language.
"Language" by Edward Sapir
"A Middle High German Primer" by Joseph Wright
Beaufort is neither Bofort nor Boofort nor Biufort, but Bueft, the u pronounced like the umlauted u in German.
"Letters from Port Royal" by Various
Also, following a practical and common convention, I have replaced the umlaut with a following letter "e".
"Practical Taxidermy" by Montagu Browne
The presence of a Hunnish =umlaut= over the =u= adds insult to injury!
"Writings in the United Amateur, 1915-1922" by Howard Phillips Lovecraft

In news:

When you start getting this freaky with vowel placement, when you have to throw around umlauts, you know that things are getting out of control.
What's in an Umlaut .