In linguistics, a simulfix is a type of affix that changes one or more existing phonemes in order to modify the meaning of a morpheme. Linguistics is the scientific study of human language, and someone who engages in this study is called a linguist or linguistician. ... An affix is a morpheme that is attached to a base morpheme such as a root or to a stem, to form a word. ... In human language, a phoneme is a set of phones (speech sounds or sign elements) that are cognitively equivalent. ... In morpheme-based morphology, a morpheme is the smallest language unit that carries a semantic interpretation. ...
Examples of simulfixes in English are generally considered irregularities, all of which left over from pluralization rules that existed before the Great Vowel Shift. They include: The Great Vowel Shift was a major change in the pronunciation of the English language, generally accomplished in the 15th century, although evidence suggests it began as early as the 14th century. ...