Sentence:  Terms related to familicide include filicide (the killing of one's child or children), uxoricide (the killing of one's wife), <WSD>fratricide</WSD> or sororicide (the killing of one's brother or sister), avunculicide (the killing of one's uncle), and nepoticide (the killing of one's nephew). 
Meaning of the word marked with <WSD> tags:  The killing of one's brother (or sister).