<p><strong>Noun</strong></p><ul><li>Phonetics, Orthography: A diacritic (¨) used over a vowel, as ä, ö, ü, to indicate a vowel sound different from that of the letter without the diacritic, especially as so used in German. Compare dieresis (def 2). Also called vowel mutation.</li><li>Linguistics, Phonetics: (in Germanic languages) assimilation in which a vowel is influenced by a following vowel or semivowel.</li></ul><p><strong>Verb</strong></p><ul><li>(used with object) Linguistics, Phonetics: To modify by umlaut.</li><li>Phonetics, Orthography: To write an umlaut over.</li></ul><p><strong>End of Response</strong></p>