Definition - What does Downhole Motor mean?
A Downhole Motor, also known as a mud motor is a positive-displacement motors that is used during field drilling operations to provide rotational power to drill bits and other downhole tools. The unique feature about downhole motors is that they are powered by the drilling mud itself. The motor converts the hydraulic power of the fluid into mechanical power so as to rotate the bit.
Petropedia explains Downhole Motor
Downhole motors provide rotational power to drill bits and other downhole tools. Such types of positive displacement motors have downhole turbine motors which are powered by drilling fluids. They are connected to the drill bits and allow the rotation of the drill bit and other downhole drilling equipment and tools without the need for rotating the drill strings located above the equipment. Such mud motors are extensively used in directional drilling, performance drilling, straight hole drilling, under reaming, milling and coring operations.