A pluricentric language is a language with several standard versions. This situation usually arises when language and the national identity of its native speakers do not coincide.
Examples
English
For example, English is a pluricentric language, with marked differences in pronunciation and spelling between the UK and the US, and a variety of accents of those and other English-speaking countries. It is usually considered a symmetric case of a pluricentric language, because no variety clearly dominates culturally. Statistically, however, American English speakers comprise more than 70% of native English speakers, with British English a distant second at 16% and other varities have less than 5% each.
German
By contrast, Standard German is often considered an asymmetric case of a pluricentric language, because the standard used in Germany is often considered dominant, mostly because of the sheer number of its speakers and their frequent unawareness of of the Austrian and Swiss varieties. While there is a uniform stage pronunciation (the Siebs Dictionary) which is used in theatres all across German-speaking countries, this is not true for the standards applied at public occasions in Austria and Switzerland, which differ in pronunciation, vocabulary, and sometimes even grammar. This also sometimes applies to news broadcasts even in Bavaria, i.e. a region within Germany with a strong separate cultural identity. The varieties of Standard German used in those regions are to some degree influenced by the respective dialects (but by no means identical with them), by specific cultural traditions (e.g. in culinary vocabulary, which differs markedly across the German-speaking area of Europe), and by different terminology employed in law and administration. A list of Austrian terms for certain food items has even been incorporated into EU law, even though it is clearly incomplete.