Dialect continuum

A dialect continuum or dialect area was defined by Leonard Bloomfield as a range of dialects spoken across some geographical area that differ only slightly between neighboring areas, but as one travels in any direction, the differences accumulate in such a way that speakers from opposite ends of the continuum are no longer mutually intelligible. (It isanalogous to a ring species in evolutionary biology.) The lines that can be drawn between areas that differ with respect to any feature of language are called isoglosses.

According to the abstand and ausbau languages paradigm, dialects can be considered abstand languages (stand-alone languages by linguistic distance). However, they can be seen as dialects of a single language as well, provided that a common standard language exists through which communication is possible (a Dachsprache).

In sociolinguistics, a language continuum is said to exist when two or more different languages or dialects merge into each other without a definable boundary. That happens, for example, across large parts of India or the Maghreb. Historically, it also happened in various parts of Europe such as in a line stretching from Portuguese to Walloon (in Belgium); from Portuguese to the southern Italian languages; and between German and Dutch.