1 [U] causing sth to catch fire 着火; 点火; 发火.
2 [C] electrical mechanism that ignites the mixture of explosive gases in a petrol engine （汽油发动机的）发火装置, 点火装置, 点火开关
*switch/turn on the ignition 打开点火开关.
the electrical part of a vehicle's engine that makes it start working
[C usually singular]
the place in a car where you put in a key to start the engine
the act of starting to burn or of making something start to burn