The ratio (greater than unity) of the volumes of the spaces within a cylinder enclosed by the extreme positions of the piston.
Note: 1 The closed extreme position of the piston is called top dead centre.
Note: 2 A higher compression ratio produces a larger power output for a given fuel consumption.
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM