Abusive Family? Is it even Abuse?

[AdrienneSRivera]

One of my best friends who, in the beginning, of the year told me and my other friends that she had seen her dad beat up her brothers at around her age. She also told us that her mom has threatened to beat her up. I'm starting to get really scared for her. I have known her for 4 to 5 years and she doesn't lie. I have tried to tell my parents, who are friends who her parents, but they won't listen and tell me I'm making it up. I'm not even sure if what my friend is describing is abuse. And if it is, what do I do? Help!