Why is benzyne an intermediate? I've always seen benzyne (benzene with a triple bond) classified as an "intermediate". I really don't see why it needs to be an intermediate, though. The possible reasons I can come up with are flimsy:


It has an unstable sp2–sp2 $\pi$ bent bond: we have bent bonds with more angle strain in cyclopropane, which is not an intermediate. Though those bonds are $\sigma$ bonds.
It immediately reacts with itself to form a dimer, biphenylene, in the absence of other reagents: there are many other molecules which spontaneously dimerize (eg $\ce{NO2}$ at certain temperatures), yet they are not classified as "intermediates".


So, what makes benzyne an "intermediate"?  

More generally (but possibly too broad), what makes a molecule an "intermediate"?
Intermediate is a middle step in the chemical process: reactants -> intermediate(s) -> products. Benzyne is formed from benzene and is highly reactive. Thus, it is never the first or last step of the process. To my knowledge benzyne is rarely observed as a product, because its reacting fast with other molecules because its triple bond.

What makes a molecule an intermediate? It is a highly reactive "middle product" of a reaction.
See here and there.