A Dictionary of Linguistics and Phonetics David Crystal

mutual intelligibility 319
mutual intelligibility A criterion used in linguistics, referring to the ability of
people to understand each other. If two varieties of speech are mutually intelligible,
they are strictly dialects of the same language; if they are mutually
unintelligible, they are different languages. The criterion seems simple, but there
are many problem cases. Two varieties may be partially intelligible – for example,
because they share some vocabulary. Also, political or cultural factors may
intervene, causing two mutually intelligible varieties to be treated as different
languages (e.g. Swedish and Danish) or two mutually unintelligible varieties to
be treated as the same language (e.g. the so-called ‘dialects’ of Chinese).