| Noun | 1. | cylinder block - a metal casting containing the cylinders and cooling ducts of an engine; "the engine had to be replaced because the block was cracked"internal-combustion engine, ICE - a heat engine in which combustion occurs inside the engine rather than in a separate furnace; heat expands a gas that either moves a piston or turns a gas turbine reciprocating engine - an internal-combustion engine in which the crankshaft is turned by pistons moving up and down in cylinders | |