Defined as 'a short axle that carries one of the front steered wheels of a motor vehicle and is capable of limited angular movement about a kingpin,' a stub axle connects a drive shaft to an outer axle yoke in order to transmit the torque from the outer yoke to the wheel.
If you've damaged a stub axle, perhaps by clipping a curb or as the result of a minor collision, then you need to replace it.

Stub axles

for any car are widely available at Eurocarparts.com.