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The closed, often detachable, end of a cylinder in an internal-combustion engine.
(Automotive Engineering) the detachable metal casting that fits onto the top of a cylinder block. In an engine it contains part of the combustion chamber and in an overhead-valve four-stroke engine it houses the valves and their operating mechanisms. Sometimes shortened to: head
(in a reciprocating engine or pump) a detachable plate or cover on the end opposite to that from which the piston rod or connecting rod projects.