[um.laut] n [G, fr. um- around, transformation + Laut sound] (1852) 1 a: the change of a vowel 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 (as to mark pluralization in goose, geese or mouse, mice) b: a vowel resulting from such partial assimilation
2: a diacritical mark placed over a vowel to indicate a more central or front articulation--compare diaeresis
[2]umlaut vt (1879) 1: to produce by umlaut
2: to write or print an umlaut over