common language
language variety accepted and understood by the entirety of a linguistic community, often identified with the standard or literary language or a lower register of it
Hindustani
Indo-Aryan language spoken in South Asia, comprising the two normative forms of Hindi and Urdu
standard Polish
standard variety of the Polish language
Common Czech
non-standard, interdialectal variety of Czech used for casual communicative situations
lingua franca
language used to make communication possible between groups without a common native language