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 dialects from opposite ends of the continuum are no longer mutually intelligible. (It is analogous to a ring species in evolutionary biology.[1]) The lines that can be drawn between areas that differ with respect to any feature of language are called isoglosses.[2]
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).