In linguistics, umlaut (from German "sound alternation") is a sound change in which a vowel is pronounced more like a following vowel or semivowel.
The term umlaut was originally coined by Jacob Grimm in connection with the study of Germanic languages, as umlaut had occurred prominently in many of their linguistic histories (see Germanic umlaut). While the common English plural is umlauts, the German plural is Umlaute.