It is the passageway in the cylinder head stretching from the exhaust valves to the exhaust manifold.

In engines, the opening through which a fluid discharges out of a cylinder. In gas meter, the openings through which gas leaves the metering chamber.

The passage in the cylinder head which connects the exhaust valve and the exhaust manifold. The exhaust gases pass through the port to the exhaust manifold or header. On two-stroke engines the exhaust port is cut into the cylinder wall because it does not have valves. Also see adjustable variable exhaust port