Wiktionary
n. The total volume of air/fuel mixture an engine can draw in during one complete engine cycle.
Wikipedia
Engine displacement is the swept volume of all the pistons inside the cylinders of a reciprocating engine in a single movement from top dead centre (TDC) to bottom dead centre (BDC). It is commonly specified in cubic centimetres (cc or cm), litres (l), or (mainly in North America) cubic inches (CID). Engine displacement does not include the total volume of the combustion chamber.
Usage examples of "engine displacement".
He thought that at the brain volume of Homo erectus-about 750 cubic centimeters, roughly the engine displacement of a fast motorcycle -the uniquely human qualities begin to emerge.
The green Ford lurched ahead, but Dale had vehicle mass, engine displacement, and desperation on his side.