Diglossia

Diglossia is when a group of people have two languages or dialects that they use. One is the common language they use every day, and the other is either a much older version from centuries before (for example, Arabic or Chinese) or a similar but clearly different modern-day version (for example, Norwegian with Bokmål and Nynorsk).

 Related pages 
Bilingual
Register (linguistics)

Category:Language