It is tantamount to treating someone as one's extension, an object, or an instrument of gratification. To be over protective, not to respect privacy, to be brutally honest, or consistently tactless is to abuse. To expect too much, to denigrate, to ignore are all modes of abuse. There is physical abuse, verbal abuse, psychological abuse, sexual abuse. The list is long.
Narcissists are masters of abusing surreptitiously.
You have to actually live with one in order to witness the abuse. The open and explicit abuse of another person. Abuse Narcissism is almost entirely about control. It is about re asserting one's identity, re establishing predictability, mastering the environment human and physical. The bulk of narcissistic behaviours can be traced to this panicky reaction to the remote potential for loss of control.