Your nephew and your children are First Cousins because they have at least one grandparent in common.
a nephew's kid to his aunt's kids would be their cousin.
First cousins once removed.
Your nephew as well...
You're a Great Aunt to your nephew's son, who is your great nephew.
Your wife's nephew is your nephew, but the English language has no relationship term for your nephew's wife. Just call her "my nephew's wife."
No, there is no such legal or traditional relationship as nephew-in-law. The term nephew-in-law is not recognized, as it can create confusion due to the lack of clarity in describing the actual relationship.
Your grandfather's great nephew is your second cousin.
Your nephew and your daughter are first cousins.
Neice or nephew no dummy its nephew
You are your nephew's uncle, or aunt, and his son's great uncle, or great aunt. Your nephew's son is your great nephew.
The English language has no relationship name for the wife of your great niece or great nephew.
Well, they are related but a name has not been given to that yet! :)