noun
umlaut (diacritic)
Refers specifically to the two-dot diacritic mark (¨) used in German and other languages, not the sound change itself.
ドイツ語のウムラウト符号は母音の上に付ける。
In German, the umlaut diacritic is placed above vowels.
Often used alone to refer to the umlaut phenomenon or the modified vowel sound; ウムラウト符号 explicitly means the diacritic mark.
From German 'Umlaut' plus 符号 (mark, sign).