What is "diaphoneme"

n. (label en linguistics) An (l/en: abstract) (l/en: phonological) unit that represents collectively the dialectal variants of a (l/en: phoneme).

A diaphoneme is an abstract phonological unit that identifies a correspondence between related sounds of two or more varieties of a language or language cluster. For example, the vowel that constitutes the English word eye is pronounced differently depending on dialect ( or in RP and General American, or in Scottish English, in Australian English, in Irish English, in South African English, and or in Southern American English, etc.) but, in the appropriate context, all of these variants are perceived by speakers as equivalent, and thus constitute a single diaphoneme. The word diaphone was originally used with the same meaning, but was later repurposed to refer to any of the particular variants, making the relationship between diaphoneme and diaphone analogous to that between phoneme and allophone.

Diaphonology studies the realization of diaphones across dialects, and is important if an orthography is to be adequate for more than one dialect of a language. In historical linguistics, it is concerned with the reflexes of an ancestral phoneme as a language splits into dialects, such as the modern realizations of Old English .