A law describing sound changes in the history of a language WordNet 3.0 & Open English WordNet

A sound change, in historical linguistics, is a change in the pronunciation of a language. Wikipedia

Process of language change affecting pronunciation or sound system structure Wikidata

Any process of language change that affects pronunciation (phonetic change) or sound system structures (phonological change), manifested as a replacement of one speech sound (or, more generally, one phonetic feature) by another, as the complete loss of the affected sound, or by the introduction of a new sound in a place where there previously was none. Wiktionary

Language change that affects pronunciation. Wiktionary (translation)

A rule that describes historical sound change (the change in pronunciation of a sound) in a language. Wiktionary

Rule that describes historical sound change in a language. Wiktionary (translation)