First cousin, once removed. Your parent on that side would be a first cousin to the nephew. If the nephew has children, they will be your second cousins. (Of course, your great uncle's nephew could also be your father).
not to be complicated , but if you have an uncle--> he has a nephew--> as you can see that's not complicated . And if you ask what is a uncles NEPHEW related to an uncles grandfather. in what way ....i would say the nephew is is the great gandfathers great grandson.
Your fathers brothers are your uncles. You are their nephew, or niece.
Your nephew's son is your great nephew.
Your nephew's daughter's son is your great-great nephew. Your nephew's daughter is your great niece.
I believe they would be great aunts or great uncles.
Your uncle is your child's great uncle and your grandchild's great great uncle. Your grandson is your uncles great great nephew.
The child of your nephew is your great nephew (if a son) or your great niece (if a daughter).
Your nephew's child is your great nephew (if a boy) or great niece (if a girl). You are his or her great aunt.
Your great nephew is your kids' first cousin once removed.
Your great nephew and your granddaughter are second cousins to each other.
Your grandson and your great nephew are second cousins to each other.
great nephew