The post-creole continuum or simply creole continuum refers to a situation wherein a creole language consists of a spectrum of varieties between those most and least similar to the superstrate language (that is, a closely related language whose speakers assert dominance of some sort). Due to social, political, and economic factors, a creole language can decreolize towards one of the languages from which it is descended, aligning its morphology, phonology, and syntax to the local standard of the dominant language but to different degrees depending on a speaker's status.
William Stewart, in 1965, proposed that the terms acrolect and basilect be the sociolinguistic labels for the upper and lower boundaries respectively of a post-creole speech continuum. In the early 1970s Derek Bickerton popularized these terms (as well as mesolect for intermediate points in the continuum) to refer to the phenomenon of code-switching used by some users of creole languages who also have some fluency in the standard language upon which the contact language is based. University of Chicago linguist Salikoko Mufwene explains the phenomenon of creole languages as "basilectalization" away from a standard, often European, language among a mixed European and non-European population. In certain speech communities, a continuum exists between speakers of a creole language and a related standard language. There are no discrete boundaries between the different varieties and the situation in which such a continuum exists involves considerable social stratification.
The continuum shown has the acrolect form as [aɪ ɡeɪv hɪm wʌn] (which is nearly identical with Standard English) while the basilect form is [mɪ ɡiː æm wan]. Due to code-switching, most speakers have a command of a range in the continuum and, depending on social position, occupation, etc. can implement the different levels with various levels of skill.
If a society is so stratified as to have little to no contact between groups who speak the creole and those who speak the superstrate (dominant) language, a situation of diglossia occurs, rather than a continuum. Assigning separate and distinct functions for the two varieties will have the same effect. This is the case in Haiti with Haitian Creole and French.
Use of the terms acrolect, mesolect and basilect attempts to avoid the value judgement inherent in earlier terminology, by which the language spoken by the ruling classes in a capital city was defined as the "correct" or "pure" form while that spoken by the lower classes and inhabitants of outlying provinces was "a dialect" characterised as "incorrect", "impure" or "debased".
It has been suggested (Rickford 1977; Dillard 1972) that African American Vernacular English is a decreolized form of a slave creole. Once blacks acquired recognition of equality under the law, opportunities for interaction created a strong influence of standard (American) English onto the speech of blacks so that a continuum exists today with Standard English as the acrolect and varieties closest to the original creole as the basilect.