"Contextual art is art that is dependent on its context; where some aspect of the context prefigures or is a prerequisite of the piece."
"Contextual art" in most cases, is a type term. The exception would be works that explicitly discuss or concern themselves with contextual art, in which case it could be used as a subject term.
Franklin Furnace - Leilani Dawson.
FF extrapolation based on 2/26/2007 Wikipedia definition of ‘context’, formation of term 'Conceptual art' and Rhizome Artbase definition.
1) Rhizome Artbase, "contextual": "Is site-specific, or requires a specific situation to function."
2) Wikipedia, from [“Context”, 2/26/2007]: "The context of an event, word, paradigm, change or other reality includes the circumstances and conditions which surround it; context in language use has two meanings: (a) the surrounding text or talk of a word, sentence or turn — also called 'co-text', and (b) the dimensions of the communicative situation that are relevant for the production or comprehension of discourse. Within specific academic disciplines, it has the following meanings:
"In Contemporary art, context is often used to describe everything other than the content of the piece of work. For example the way in which a painting is hung within a gallery, the political situation at the time of viewing, the amount of wine consumed at the private view."
3) Merriam-Webster Online, ["Context"], 4/9/2007: "1 : the parts of a discourse that surround a word or passage and can throw light on its meaning. 2 : the interrelated conditions in which something exists or occurs : ENVIRONMENT, SETTING <the historical context of the war>."