A machine is a thermodynamic system that uses power to apply forces and control movement to perform an action. The term is commonly applied to artificial devices, such as those employing engines or motors, but also to natural biological macromolecules, such as molecular machines.
machine, device, having a unique purpose, that augments or replaces human or animal effort for the accomplishment of physical tasks.
A machine is any device that does work. Machines make our lives a bit easier because they reduce the amount of energy, power, and time we need to get one thing done by magnifying our input force.