Umlaut

Umlaut, a German word invented by Grimm, and now used by all writers on the philology of the Teutonic tongues, including English, for a vowel change in their languages brought about on a preceding vowel by the vowel i (or e) modifying the first in the direction of e or i. It is common in German (thus gänse, the plural of gans; schlüge, the subjunctive of schlug); and there are survivals in English, as men from man, fell from fall, mice from mouse.