Answer: Neutral grounding is the process of connecting neutral point of a three phase system to ground either directly or through some circuit elements (e.g. resistance, reactance etc.) is called the in neutral grounding.
According to wikipedia,
As the neutral point of an electrical supply system is often connected to earthground, ground and neutral are closely related. Under certain conditions, a conductor used to connect to a system neutral is also used for grounding(earthing) of equipment and structures.