A stub axle is one of the two front axles that carries a wheel in a rear wheel drive vehicle. The axle is capable of limited angular movement about the kingpin for steering the vehicle. The stub axle consists of wheel bearings which support the wheel hub.
The stub axle is named so because it resembles the shape of a stub, like a truncated end of an axle, short in shape and blunt.
References
Stub axle Wikipedia(Text) CC BY-SA