Main Entry: ab·laut

Pronunciation: \ˈä-blau̇t, ˈa-; ˈäp-ˌlau̇t\

Function: noun

Etymology: German, from ab away from + Laut sound

Date: 1849

: a systematic variation of vowels in the same root or affix or in related roots or affixes especially in the Indo-European languages that is usually paralleled by differences in use or meaning (as in sing, sang, sung, song)