The euphonic modification of a root vowel sound by the influence of a, u, or especially i, in the syllable which formerly followed.
- A change in a vowel sound caused by partial assimilation especially to a vowel or semivowel occurring in the following syllable.
- A vowel sound changed in this manner. Also called vowel mutation.
- The diacritic mark (¨) placed over a vowel to indicate an umlaut, especially in German.
- To modify by umlaut.
- To write or print (a vowel) with an umlaut.