ablaut

äänteenmukaus puhekieltä The substitution of one root vowel for another, thus indicating a corresponding modification of use or meaning; vowel permutation; as, (m), (m), and (m); (m) and (m); (m) and (m), distinct from the phonetic influence of a succeeding vowel. (defdate)(R:SOED5)
puhekieltä To undergo a change of vowel.
(quote-book)
(quote-book), Zarina Estrada Fernández|year=2012|passage=This allomorph also causes the back vowel to ablaut to a low vowel.
puhekieltä To cause to change a vowel.
puhekieltä (l) (gloss)