noun
Definition: A special mark placed over a vowel in some languages, like German, that changes the way the vowel sounds. It can also refer to the change in the vowel sound itself.
Example: In German, the letter "ü" has an umlaut, which changes its pronunciation.
transitive verb
Definition: To change a vowel sound in a word, often by adding two dots above the letter, which alters its pronunciation.
Example: In German, you can umlaut the letter 'a' to create 'ä'.