Fits into the cylinder head of an internal-combustion engine and ignites the gas by means of an electric spark; SYN. sparking plug, plug.
Plug that produces an electric spark in the cylinder of a gasoline engine to ignite the fuel mixture. It consists essentially of two electrodes insulated from one another. High-voltage (18,000 v) electricity is fed to a central electrode via the distributor. At the base of the electrode, inside the cylinder, the electricity jumps to another electrode earthed to the engine body, creating a spark. See also ignition coil. sparkplug