ablaut /ˈablaʊt 
/ ▸ noun [mass noun] alternation in the vowels of related word forms, especially in Germanic strong verbs (e.g. in sing, sang, sung): [as modifier] an ablaut series.
– ORIGIN mid 19th century: from German, from ab ‘off’ + Laut ‘sound’.
EnglishOxford Dictionary of English
