A vowel change, characteristic of Indo-European languages, that accompanies a modification of grammatical function; as an example, i, a, u in sing, sang, sung. Also called gradation.
The replacement of one root vowel for the next, thus indicating a corresponding adjustment useful or definition; vowel permutation; because, get, gat, got; sing, song; hang, hung.
In philology, a substitution of one vowel for the next in your body for the cause of a word, associated a modification of use or definition: as, bind, musical organization, bound, bond, German bund; more particularly, the alteration of a vowel to indicate tense-change in strong verbs, as opposed to the addition of a syllable (-ed), such as weak verbs: as, get, gat, got; sink, sank, sunk.
a vowel whose quality or size is changed to point linguistic distinctions (such as sing sang sung track)