Transmission

noun

1. The act of transmitting, e.g. data or electric power.
2. The fact of being transmitted.
3. Something that is transmitted, such as a message, picture or a disease; the sending of such a thing.
4. The passage of a nerve impulse across synapses.
5. An assembly of gears through which power is transmitted from the engine to the driveshaft in a motor car / automobile; a gearbox.