# 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 sp2sp2 $\pi$ 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"?