10.2 SIMPLE HARMONIC MOTION AND THE REFERENCE CIRCLE
The model consists of a small ball attached to the top of a rotating turntable. The ball is
moving in uniform circular motion...on a path known as the reference circle.
Figures 10.7 & 10.8 show visually what they are studying.
So it's just a spinning thing.
I'm afraid I don't know any fancy names for something that spins, that isn't shaped like a table.
Actually, there are some tables shaped like that. (Google: very long dining tables)
I'm going to say it's a "turntable".