1) It requires a key 2) Vehicle part 
An Ignition (or starter) switch is a switch in the control system of an internal combustion engined motor vehicle that activates the main electrical systems for the vehicle. Besides providing power to the starter solenoid and the ignition system components (including the engine control unit and ignition coil) it also usually switches on power to m...
[n] - switch that operates a solenoid that closes a circuit to operate the starter
noun switch that operates a solenoid that closes a circuit to operate the starter