noun A construction in which one noun or noun phrase is placed with another as an explanatory equivalent, both of them having the same syntactic function in the sentence.
noun The relationship between such nouns or noun phrases.
noun The quality of being side by side, apposed instead of opposed, next to each other.
noun A placing of two things side by side, or the fitting together of two things.
noun The growth of successive layers of a cell wall.
noun Appositio, the addition of an element not syntactically required.
noun A public disputation by scholars.
noun A (now purely ceremonial) speech day at St Paul's School, London.