On 25 May the World Health Organisation officially updated the eleventh International Classification of Diseases (ICD) to include parental alienation.

Parental alienation occurs when one parent deliberately tries to damage the relationship the other has with his or her child. It often happens when parents are going through a not-so-amicable divorce, and a child becomes notably more distant and detached from one parent.

The child experiencing feelings of ambivalence or complete hatred of the targeted parent they once loved, while thinking their other parent is perfect & deserving of their love. In the case of a disagreement between the two parents, the child will not be interested in the side of the alienated parent.
The rejection of all contact with the targeted parent, as well as the loved ones of said parent.
Frivolous excuses when they’re questioned about why they’re rejecting the targeted parent.
While they may provide senseless explanations for the rejection, they’ll maintain that the decision was theirs, & only theirs, without influence from the other parent.
They will not feel any guilt or remorse for alienating the targeted parent.