1. A device or system which controls the rate at which energy is converted into motion. It usually consists of moving wheels and levers which fit together. English = gears.
2. A piece of equipment which uses electricity or power from an engine, especially one that has gears. English = machine.
3. Part of a machine that uses electricity or fuel to produce movement, so that the machine can work. English = motor, engine.
4. A skilled person who uses scientific knowledge to design and construct machinery, electrical devices, or roads and bridges; the skill itself. English = engineer; engineering.