Meaning

noun a diacritical mark (two dots) placed over a vowel in German to indicate a change in sound

originEtymology tree German um- Proto-Indo-European *ḱlew- Proto-Indo-European *-tós Proto-Indo-European *ḱlutós Proto-Germanic *hlūdaz Proto-West Germanic *hlūd Old High German lūt Middle High German lūt German Laut German Umlautbor. English umlaut Borrowed from German Umlaut in the 19ᵗʰ century, from um- or um (“around, re-, trans-”) + Laut (“sound”), from Old High German hlūt. More at loud.

Etymology from Wiktionary, CC BY-SA 3.0