ignition (ignitions plural )
1 n-var In a car engine, the ignition is the part where the fuel is ignited.
The device automatically disconnects the ignition.
2 n-sing Inside a car, the ignition is the part where you turn the key so that the engine starts.
3 n-uncount Ignition is the process of something starting to burn.
The ignition of methane gas killed eight men.