English▸ noun a mark ( ¨ ) used over a vowel, as in German or Hungarian, to indicate a different vowel quality, usually fronting or rounding.
▪ (especially in Germanic languages) the process by which a back vowel becomes front in the context of another front vowel, resulting, e.g., in the differences between modern German Mann and Männer or (after loss of the inflection) English man and men.
▸ verb [with object] modify (a form or sound) by using an umlaut:
the color of prothetic vowels, unless umlauted by the next syllable, was that of the laryngeal which was vocalized.
– ORIGIN mid 19th century : from German Umlaut, from um ‘about’ + Laut ‘sound’.