Good question Myr - I had not heard of them being called that; my gran was a florist (Kent, UK) and just referred to them as 'bases' AFAICR, but no doubt someone else can shed more light.

Thanks too for the pic of the musical frogs - I had thought it referred only to the metallic knob, rather than the entire endpiece of the bow. Going bach to basics has helped me get a handel on it.