Answer: ablaut
AnswerCrossword Clue
ABLAUTApophony
ABLAUTVowel change in related words
ablauta 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)
ablauta variation in root vowels of verb forms
ablaut(in Indo-European languages) regular alternation in the internal phonological structure of a word element, esp. alternation of a vowel, that is coordinated with a change in grammatical function or combination, as in English sing, sang, sung, song;