No thanks to the many dictionary definitions I found:
An appositive is a noun or noun phrase that renames another noun right beside it. The appositive can be a short or long combination of words. (http://www.chompchomp.com/terms/appositive.htm)
Apposition is a grammatical construction in which two elements, normally noun phrases, are placed side by side, with one element serving to define or modify the other. When this device is used, the two elements are said to be in apposition. (http://en.wikipedia.org/wiki/Apposition)
A noun, noun phrase, or series of nouns placed next to another word or phrase to identify or rename it. (http://grammar.about.com/od/ab/g/apposterm.htm)
Basically, it’s a noun or noun phrase used as an adjective. Ta da!
Bill the milkman
Jessica, Web Producer
Elm Street, the twistiest road in Springfield