Diglossia

When diglossia occurs, two varieties of the same language or dialect coexist within a speech community, and a fairly clear compartmentalization is made by speakers.

The term was first defined by American linguist Charles Ferguson in 1959.

Diglossia distinguishes between:

• A Low (L) variety, which usually corresponds to day-to-day vernacular used in conversation.
• A High (H) variety, frequently used in formal environments like literature or academics, and often related to written communication.

Some examples of highly diglossic languages are:

• Arabic, where colloquial varieties from different regions coexist with Classical Arabic as used in formal education and in the Quran.
• Greek, where Demotic is the popular spoken language and Katharevusa, derived from Classical Greek, is a prestige dialect used by scholars.
• Swiss German (dialect), spoken informally and adapted to Standard German in educational and informative settings.
• Brazilian Portuguese (dialect), which makes a clear distinction between the spoken variety and the written variety, derived from European Portuguese and commonly used in formal education.
• Jamaican Patois (dialect), spoken as the informal vernacular of the region, in contrast to Standard English (H), frequently used by institutions, businesses and media.
• Haitian Creole (dialect), used coloquially as an L variant, in contrast to Standard French (H).

In the past, diglossia has also been observed in multiple occasions:

• Latin made a clear distinction between Classical Latin (H), commonly used by Roman literates and then by the Church, and Vulgar Latin (L), spoken colloquially.
• Italian used to present their own H variety (the Tuscan dialect, used by poets, literates and high-ranking officials), in contrast to the Standard Italian variety that developed with the advent of television and political unification.

When three varieties coexist, this phenomenon is called triglossia.