in the spud gun sense it is a combination of Pneumatic cannon (pressurized chamber) and a combustion cannon (combustible fuel with ignition).
In that sense, technically, a metered combustion is also a hybrid. MAC (Multiple Atmospheric Combustion) could possibly be a better acronym but I'm really just talking out of my a$$ here.
I believe the QDV is actually a commercial valve and Tech was just the first to make it suitable for spudguns. In fact, Quick Dump Valve may actually be the original name of the commercial valves. I think MythBusters use them when they have those huge red propane tank looking chambers which seem to have no valve.
Anyway, this discussion is similar to that of the hybrid one we had a little while ago. There's no point changing the name as everyone knows what it already means and changing the name would just create more confusion. While we're nitpicking, some of Tech's valves are designed to open slowly, does that mean we have to call them a Slow Dump Valve?
POV (pilot operated valve)
NPV (non piloted valve)
That could cause confusion with hammer valves and the like.
At the moment everyone knows a QEV is generally a commercially bought piston valve (unless you're French), a piston valve is generally homemade, a QDV is a valve that operates with the same principles as Tech's design, a hybrid is a multiple atmosphere combustion and an advanced combustion (while not being particularly advanced) is a metered combustion with perhaps a fan.