And:It is fair to say that in physics, there is no broad consensus as to an exact definition of matter, and the term "matter" usually is used in conjunction with some modifier.
http://en.wikipedia.org/wiki/MatterThe quark-lepton building blocks interact through a number of fundamental forces, and are described by the Standard Model of particle physics (gravity so far included only classically; see quantum gravity and graviton).[12] Interactions are mediated by field quanta or force carriers, of which the W-boson and the photon are examples.[13] The interactions are not themselves building blocks, and consequently neither are their quanta. As one consequence, energy cannot always be related to matter: for example, photons possess energy (see Planck relation); however, photons commonly are distinguished from matter.[14] Also, mass cannot always be related to matter: certain particles are massive, such as the W-boson, but are not matter. Although the field quanta by themselves are not matter, in conjunction with a complex of building blocks like an atom or a hadron, they contribute to the invariant mass of the combination, for example, through a binding energy.
(My emphasis in the latter quote)
After all that money spent in basic science research, nobody knows what is. I want my money back.
Gotcha...
Shit...now I'm even more confused...
To find out, I suggest you apply for a research grant. 
