Akademik

electrical device that fits into the cylinder head of an internal-combustion engine and ignites the gas by means of an electric spark

ˈspark plug [spark plug spark plugs] (also plug) (BrE also ˈsparking plug) noun

a part in a car engine that produces a ↑spark (= a flash of electricity) which makes the fuel burn and starts the engine

See also: ↑plug