Your nephew's daughter is your great niece and you are her great aunt (if you are a woman) or her great uncle (if you are a man).
Your nephew's daughter is your great niece. You are her great aunt (if you are a woman) or her great uncle (if you are a man).
Great aunt or uncle.
Your nephew's daughter's son is your great-great nephew. Your nephew's daughter is your great niece.
Daughter in law
Your nephew's daughter is your great niece. Her child is your great great niece or great great nephew.
Well the daughter will be your grandaughter and you will be a grandmother/grandfathther.
Your nephew and your daughter are first cousins.
Your brother's son's daughter is your great-niece. In simpler terms, she is the daughter of your nephew. Thus, you are her great-uncle or great-aunt.
Your nephew's daughter's son is your great grand nephew (or great great nephew). You are his great great aunt if you are a woman, or his great great uncle if you are a man.
Your nephew's daughter is your great niece. You are her great aunt (if you are a woman) or her great uncle (if you are a man).
Your nephew's daughter is your great niece. Her son is your great great nephew. You are his great great aunt (if you are a woman) or his great great uncle (if you are a man).