Apposition is a grammatical construction in which two elements, normally noun phrases, are placed side by side so one element identifies the other in a different way. The two elements are said to be in apposition, and one of the elements is called the appositive, but its identification requires consideration of how the elements are used in a sentence.

For example, in these sentences, the phrases Alice Smith and my sister are in apposition, with the appositive identified with italics:

• My sister, Alice Smith, likes jelly beans.
• Alice Smith, my sister, likes jelly beans.

Traditionally, appositions were called by their Latin name appositio, derived from the Latin ad ("near") and positio ("placement"), although the English form is now more commonly used.

Apposition is a figure of speech of the scheme type and often results when the verbs (particularly verbs of being) in supporting clauses are eliminated to produce shorter descriptive phrases. That makes them often function as hyperbatons, or figures of disorder, because they can disrupt the flow of a sentence. For example, in the phrase: "My wife, a surgeon by training,...", it is necessary to pause before the parenthetical modification "a surgeon by training".