This is what the dictionary says:-
Bicycle: A vehicle consisting of two wheels held in a frame one behind the other, propelled by pedals and steered with handlebars attached to the front wheel.
Motorcycle: A two-wheeled vehicle that is powered by a motor and has no pedals.
E-bike: A bike that can be powered by electricity as well as propelled by pedals
As this thread has certainly demonstrated, the generic term E-bike covers an extremely wide range of applications. At one end of the spectrum we have relatively low powered lightweight e-bikes that are still mostly propelled by pedalling with a proportional motor assist. While at the other end of the spectrum we have powerful heavyweight e-bikes with throttles and pedals with high levels of non-proportional assist. Plus about a 100 shades of grey in-between.