Umlaut

Umlaut, name given by Grimm to the modification of a vowel in a syllable through the influence of a vowel in the succeeding.

Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)

Umbria * Una
Ulrici, Hermann
Ulster
Ultimus Romanorum
Ultramontanism
Ulugh-Beg
Ulysses
Ulysses' Bow
Uma
Umballa
Umbria
Umlaut
Una
Uncial Letters
Uncle Sam
Unconscious, The
Understanding, The
Undine
Undulatory Theory
Unearned Increment
Unicorn
Uniformity, Act Of