Apophony
| Sound change and alternation |
|---|
| Fortition |
| Dissimilation |
In linguistics, apophony (also known as ablaut, (vowel) gradation, (vowel) mutation, alternation, internal modification, stem modification, stem alternation, replacive morphology, stem mutation, or internal inflection) is an alternation of vowel (quality) within a word that indicates grammatical information (often inflectional).