What term is used to describe the regular shifting between different dialects?

The term that describes the regular shifting between different dialects is "code-switching." This concept refers to the practice of alternating between different languages or dialects within a conversation or discourse, often influenced by social context, audience, or specific conversational topics. Code-switching can occur for a variety of reasons, including linguistic identity, social dynamics, or to better express a thought that may be more effectively articulated in one dialect over another.

In contrast, dialectology refers to the study of dialects, including their features and distribution, rather than the practice of switching between them. Diglossia describes a situation where two distinct varieties of the same language coexist within a community, with one variety used in formal contexts and the other in informal ones, but it doesn't emphasize the frequent and fluid switching that characterizes code-switching. Lastly, a pidgin is a simplified language that develops as a means of communication between speakers of different native languages, used in specific contexts rather than as a matter of regular conversational fluidity.

Thus, the most fitting term for the act of regularly shifting between dialects is code-switching.