The term MILL CHANNEL can be summarized as a RACE of water that is used to power a mill. It is a channel of water that is diverted from a river or stream and used to turn a wheel or turbine, which in turn powers a mill. This type of channel has been used for centuries to power mills, and is still used today in some parts of the world. The crossword solution for this term is RACE, which is an apt description of the flow of water through the channel.