Grant Erwin writes:

If you try a quick google for
compressor cfm psi
you will instantly see what I mean - everyone specifies their
compressors at a cfm @ a psi.

Right. That's exactly what I have been saying. CFM must always have an
associated pressure to indicate performance. The mass of air is
nevertheless always referenced to the density and pressure of free air
(1 atm), not the stated psi.

For example, my compressor will deliver 6 CFM at 90 psi. That means it
will inhale 6 cubic feet of free air, and push it out at 90 psi.

So it's all a matter of a simple misunderstanding. In the circles you
travel in, CFM has some specialized meaning. To the rest of the world,
it simply means cubic feet per minute.

No, there is no misunderstanding. CFM with respect to air compressors
only means what I have been describing. It has nothing to do with the
"circles" I travel in.

I would recommend _Machinery's Handbook_ on this subject if you are
still unconvinced.

So what do you call simple cubic feet per minute as a volumetric gas
flow?

Cubic feet per minute.