In this context, the particles that appear in the Standard Model. So a quasiparticle can be understood in terms of the underlying structure of matter ( a crysta

In this context, the particles that appear in the Standard Model. So a quasiparticle can be understood in terms of the underlying structure of matter ( a crystal in this case), a 'real' particle can not be understood in terms of some underlying mechanism. Granted, "can not be understood in those terms yet" is preliminary and a not really satisfying definition.