[{"Bold_text": "noun", "List Items": ["Phonetics, Orthography.a diacritic (¨) used over a vowel, asä, 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 ) dieresis ( def 2 ).", "Also called vowel mutation vowel mutation.Linguistics, Phonetics.(in Germanic languages) assimilation in which a vowel is influenced by a following vowel or semivowel."]}, {"Bold_text": "verb (used with object)", "List Items": ["Linguistics, Phonetics.to modify by umlaut.", "Phonetics, Orthography.to write an umlaut over."]}]