umlaut Definition

a diacritical mark ¨ placed over a vowel to indicate a more central or front articulation

the change of a vowel (such as \ü\ to \ē\ in goose, geese) that is caused by partial assimilation to a succeeding sound or that occurs as a reflex of the former presence of a succeeding sound which has been lost or altered

a vowel resulting from such partial assimilation

to produce by umlaut

to write or print an umlaut over