An apposition is a noun or a phrase used alongside another noun or phrase with the same function. Appositions may be restrictive or non-restrictive, and are used to clarify or explain, offering more information than either word or phrase on its own. For example, in the sentence “My neighbor Sam stopped by,” the phrase “my neighbor” and the proper noun “Sam” both identify the person who is the subject of the sentence. In this sentence, these parts form an apposition, with each half helping to define the subject.
A restrictive apposition provides details which specify or further define the first noun. Referring once again to the above sample sentence, the phrase “my neighbor” is further clarified by the name “Sam”, limiting or “restricting” the list of neighbors to the one named Sam. Restrictive appositions typically have a strong impact on the meaning of a sentence. Commas are not generally used to separate the halves of a restrictive apposition.
Non-restrictive appositions do not refine definitions but instead offer additional details about the initial noun or phrase. By inverting the phrasing in the sample sentence to “Sam, my neighbor, stopped by,” the phrase “my neighbor” does not limit the meaning of the proper noun “Sam.” Instead it gives additional information about Sam, making this a non-restrictive apposition. Typically, commas are used to set portions of non-restrictive appositions apart.
The false title is a common form of apposition, especially in journalism. A false title is a label or unofficial title attached to a noun. For instance, in the sentence “Alleged criminal John Doe appeared in court today,” the phrase “alleged criminal” is used as a pseudo title for John Doe, resulting in a restrictive apposition. This should not be confused with genuine titles such as Doctor or Reverend, which are not appositions and are instead used as part of the proper noun’s name.
Some appositive phrases break away from the simple syntax common of most restrictive and non-restrictive appositions. “Of” is sometimes used to give weight to a phrase, such as in “the city of Philadelphia.” The first example can be restructured as “Sam, a neighbor of mine.” The song "Molly Malone" begins “In Dublin’s fair city,” where the possessive “’s” is used to form an appositive phrase, but this is a highly unusual structure.
Outside of this grammatical structure, the word “apposition” has other meanings. For instance, it can refer to the juxtaposition of two objects placed near one another for contrast. It is also used to describe both the layered growth of cells along a cell wall and the wall created by this process.