IPA: /dɪˈɡlɒs.i.ə/
KK: /dɪˈɡlɑːsiə/
A situation in language use where two different forms of a language are used by a community, often with one being more formal and the other more casual.
In some regions, diglossia is common, where people switch between a formal language for writing and a colloquial one for speaking.
Diglossia is formed from "di-" (meaning two) and "glossa" (from Greek, meaning tongue or language). The term describes a situation where two languages or dialects are used by a single language community, typically with one being more formal and the other more colloquial.
Think of 'two' ('di-') languages or dialects ('glossa') being used in the same community — that's what diglossia means.