ig·ni·tion 
(ĭg-nĭshən)
(ĭg-nĭshən)n.
1. The act or process of igniting something: the ignition of the fuel in a piston.
2.
a. An electrical system, typically powered by a battery or magneto, that provides the spark to ignite the fuel mixture in an internal-combustion engine.
b. A switch that activates this system.