apposition

(noun) a grammatical relation between a word and a noun phrase that follows. Example: "`rudolph the red-nosed reindeer' is an example of apposition."

(noun) (biology) growth in the thickness of a cell wall by the deposit of successive layers of material.

(noun) the act of positioning close together (or side by side). Synonyms: juxtaposition, collocation. Example: "It is the result of the juxtaposition of contrasting colors."