What does abuse mean

My friend always tell me how my parents are abusive when I talk about it but Ive always begged them not to tell anyone before them my real mom went to jail and me and my brother went to are grandma she had us for a year the next person we went to was my aunt and her husband SA'd me when I was 1 or 2 and after a year there I went to my uncle who I live with now and call my parents my mom has put a gun to my head and knifes to our necks they laugh when I express my feelings and turned my emotions against me and tell me how it my fault I don't know I just want to know what abuse means and if I'm actually being abused.