That's always an issue in Gretsch books. Gretsch always called it their first solidbody and it had to be a substitute for Fender basses and Gibson EB basses. But it really is 'semisolid.'
But:
There are a lot of Les Pauls with chambered bodies too. The girl-versions, some Epiphones and modern LPs, the Peter Frampton sig and I believe the new Slash sig has it too. Gibson state that they can't find wood as light as they had in the sixties. Making a guitar more hollow to the weight of a solid lightweight guitar, gives a same sound. Peter Frampton stated in an interview some years ago that his first prototype was heavier and different sounding than his own guitar. They made the chambers so it weighs exact the same as the real old Frampton guitar and the sound was spot on! of course this could be a nice selling story only.
But to come to the point: Chambered Les Pauls are never called semisolid either.