My understanding is that lots of languages have distinct names for many relationships. I read a funny article on the subject years ago by a man proposing English names for every relationship imaginable. I think the title was "Are you a Funkle?" That's what your father's brother would be. Your mother's brother would be your Munkle. Your sister's daughter would be your Siece, and your brother's daughter would be your Biece. It got complicated when he got to the in-laws, but there was a system. Anyway, we call in our family we like "inlaw-inlaws" better than "outlaws".