I would define a "Neutral" as the connection to a center tapped 1 phase transformer coil, either at the X2 / X3 jumper point for a split coil transformer, or a physical 50% tap of a 240 volt coil, in which a circuit can be formed from either one of the coil's ends to the center tap. It can carry inbalanced current when designed around multi wire 1 phase circuits.
I would not consider the grounded conductor on a 4 wire Wye system to be a "Neutral", but a "Common", due to the load characteristics.
Let me know if this is what you were looking for!
S.E.T.
