multidialectal

adjective

mul·​ti·​di·​a·​lec·​tal ˌməl-tē-ˌdī-ə-ˈlek-tᵊl 

-ˌtī-

: using or able to use more than one dialect of the same language

We are all multidialectal, all of the time, mastering levels of formality, adjusting content to context in speech as well as writing.

—Dennis Baron

Word History

First Known Use

1959, in the meaning defined above