Mutual intelligibility


In linguistics, mutual intelligibility is a relationship between different but related language varieties in which speakers of the different varieties can readily understand each other without prior familiarity or special effort. Mutual intelligibility is sometimes used to distinguish languages from dialects, although sociolinguistic factors are often also used.
Intelligibility between varieties can be asymmetric; that is, speakers of one variety may be able to better understand another than vice versa. An example of this is the case between Afrikaans and Dutch. It is generally easier for Dutch speakers to understand Afrikaans than for Afrikaans speakers to understand Dutch.
In a dialect continuum, neighbouring varieties are mutually intelligible, but differences mount with distance, so that more widely separated varieties may not be mutually intelligible. Intelligibility can be partial, as is the case with Azerbaijani and Turkish, or significant, as is the case with Bulgarian and Macedonian.

Types

Asymmetric intelligibility

Asymmetric intelligibility refers to a relationship between two partially mutually intelligible languages in which one group of speakers has greater difficulty understanding the other language than vice versa, due to various linguistic or sociocultural factors. For example, if one language is related to another but has simplified its grammar, the speakers of the original language may understand the simplified language, but not vice versa. To illustrate, Dutch speakers tend to find it easier to understand Afrikaans as a result of Afrikaans's simplified grammar.

Among sign languages

s are not universal and usually not mutually intelligible, although there are also similarities among different sign languages. Sign languages are independent of spoken languages and follow their own linguistic development. For example, British Sign Language and American Sign Language are quite different linguistically and mutually unintelligible. The grammar of sign languages does not usually resemble that of the spoken languages used in the same geographical area. To illustrate, in terms of syntax, ASL shares more in common with spoken Japanese than with English.

As a criterion for distinguishing languages

Some linguists use mutual intelligibility as the primary linguistic criterion for determining whether two speech varieties represent the same or different languages.
A primary challenge to this view is that speakers of closely related languages can often communicate effectively when they choose to. For example, in the case of transparently cognate languages recognized as distinct such as Spanish and Italian mutual intelligibility is neither binary nor absolute, but exists along a spectrum, influenced by numerous speaker-specific and contextual variables.
Classifications may also shift for reasons external to the languages themselves. As an example, in the case of a linear dialect continuum, the central varieties may become extinct, leaving only the varieties at both ends. Consequently, these end varieties may be reclassified as two languages, even though no significant linguistic change has occurred within the two extremes during the extinction of the central varieties.
Furthermore, political and social conventions often override considerations of mutual intelligibility. For example, the varieties of Chinese are often considered a single language, even though there is usually no mutual intelligibility between geographically separated varieties. This is similarly the case among the varieties of Arabic, which also share a single prestige variety in Modern Standard Arabic. In contrast, there is often significant intelligibility between different North Germanic languages. However, because there are various standard forms of the North Germanic languages, they are classified as separate languages.
It is often claimed by linguists that mutual intelligibility is completely gradual and thus not very useful as a criterion for demarcating boundaries between languages, but a 2021 study suggests that it can allow for meaningful segmentation.

Within dialect continua

North Germanic

Northern Germanic languages spoken in Scandinavia form a dialect continuum where the two furthermost dialects have almost no mutual intelligibility. As such, spoken Danish and Swedish normally have low mutual intelligibility, but Swedes in the Öresund region, across the strait from the Danish capital Copenhagen, understand Danish somewhat better, largely due to the proximity of the region to Danish-speaking areas. While Norway was under Danish rule, the Bokmål written standard of Norwegian developed from Dano-Norwegian, a koiné language that evolved among the urban elite in Norwegian cities during the later years of the union. Additionally, Norwegian assimilated a considerable amount of Danish vocabulary as well as traditional Danish expressions. As a consequence, spoken mutual intelligibility is not reciprocal.

Romance

Because of the difficulty of imposing boundaries on a continuum, various counts of the Romance languages are given. For example, in The Linguasphere register of the world's languages and speech communities, David Dalby lists 23 languages based on mutual intelligibility:
The non-standard vernacular dialects of Serbo-Croatian diverge more significantly from all four normative varieties of Serbo-Croatian. Their mutual intelligibility varies greatly between the dialects themselves, with the standard Shtokavian dialect, and with other languages. For example, Torlakian, which is considered a subdialect of Serbian Old Shtokavian, has significant mutual intelligibility with Macedonian and Bulgarian.

List of mutually intelligible languages

Afroasiatic

Germanic