Pedelec stands for Pedal Electric Cycle. While pedaling the rider gets additional power from the electric drive system.
The control of the motor output of a pedelec is linked to the riders pedaling contribution by means of a movement or power sensor. In other words: the electric motor is activated as soon as the rider starts to pedaling and deactivated as soon as the rider stops pedaling.
We are familiar with this power-assist principle in the power steering system of a car.
Pedelecs, first introduced by Yamaha in 1994, have the potential to become a vehicle category of its own. It works like a bicycle and is as comfortable as a motor cycle.
More on the terminology of Pedelec and E-Bike can be found in the graduation paper by Susanne Bruesch (mainly in German).