Intelligibility
For individuals to achieve moderate proficiency or understanding in a language (called L2) other than their first language (L1) typically requires considerable time and effort through study and/or practical application. However, many groups of languages are partly mutually intelligible, i.e. most speakers of one language find it relatively easy to achieve some degree of understanding in the related language(s). Often the languages are genetically related, and they are likely to be similar to each other in grammar, vocabulary, pronunciation, or other features. An example of a pair of genetically related languages is a creole and a parent language.
Intelligibility among languages can vary between individuals or groups within a language population according to their knowledge of various registers and vocabulary in their own language, their interest in or familiarity with other cultures, the domain of discussion, psycho-cognitive traits, the mode of language used (written vs. oral), and other factors.
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