Engine displacement
The total volume of an engine's cylinders, usually given in liters (like 2.0L).
Displacement is the combined volume of all of an engine's cylinders, expressed in liters. A 2.0L four cylinder moves two liters of air and fuel through its cylinders per full cycle.
Bigger displacement traditionally meant more power and more fuel use. Turbocharging has loosened that link: a modern 2.0L turbo can out-pull an older 3.5L while using less fuel in normal driving.