Apposiitsus

Apposiitsus, or apposition, is a grammatical construction in which a noun phrase immediately follows another noun to rename it or provide non-essential information about it. The appositive shares the same referent as the head noun and functions as an added identification rather than as a dependent modifier.

In English, the usual rule is about punctuation: non-restrictive appositions are set off by commas (or dashes), while restrictive appositions may appear without commas. For example: "London, the capital of the United Kingdom, is a major financial center." Here the phrase "the capital of the United Kingdom" is an appositive providing extra information about London. In contrast, a restrictive apposition would be used when the information is essential to identify the referent, and it might lack surrounding punctuation.

Two common functions characterize appositions. First, renaming or identifying the referent, as in "Marie Curie, a physicist, conducted pioneering research." Second, explaining or elaborating on the referent, as in "The author George Orwell, born Eric Blair, wrote 1984." Appositive phrases can be noun phrases, short descriptors, or longer noun clauses, and they may vary in position, though they typically follow the head noun.

Cross-linguistically, apposition is widespread and subject to language-specific punctuation and agreement rules. In Estonian linguistic terminology the construction is called apposiitsus. Across languages, appositions provide concise supplementary information and help clarify identity or offer incidental detail without altering the base referent. See also: appositive, appositive clause.