Not just the cylinder actually. The volume displaced by piston movement from top dead center to bottom dead center is the swept volume (SV), which is used to calculate total displacement of the engine for rating and advertising purposes. Any space above the piston at top dead center is combustion chamber volume. This is easiest to understand with a flat topped piston. The CCV includes the thickness of the head gasket, the recession or protrusion of the piston within the block, and the combustion chamber in the head itself. If the piston is domed, the domes volume is subtracted, and if dished, it is added to the CCV. Once the two volumes are determined, the formula is quite simple. CCV plus SV divided by CCV.

When someone descibes an engine as a 2.0 litre, or a 302 cu. in., what they are talking about is the swept volume of all cylinders. Ferrari, and a few others, rate their engines (and name their cars) by the swept volume of one cylinder, like 365/GTB-4 which means a V-12 engine of 365 cm3 displacement per cylinder. Detroit Diesel used to do this too, a common two stroke engine of the past was the 8V-71, which meant eight cylinders, V arrangement, and 71 cubic inches per cylinder.