Your first cousin's sibling (parent of the nephew) is also your first cousin, so in that case the nephew is your first cousin, once removed.
However, it's possible that the nephew is the son of one of your cousin's spouse's siblings, which makes him best described as "no relation."
Then there's half-siblings, and step-siblings.... the bottom line is you're probably best off leaving it as "my cousin's nephew" except in the specific "cousin once removed" case already mentioned.
Your first cousin's nephew is the child of the brother or sister of your first cousin. Thus, your first cousin's nephew is the child of another one of your first cousins. The child of any first cousin is your first cousin, once removed. Therefore your first cousin's nephew is your first cousin, once removed.
Your nephew is your brother's or your sister's son. Your first cousin is also your brother's and your sister's first cousin. Your nephew and your first cousin are therefore first cousins, once removed, to each other. If your first cousin has a child, that child and your nephew are second cousins to each other.
First cousins once removed. Your child and your nephew are first cousins and there is one generation difference.
Your nephew and your first cousin are first cousins, once removed, to each other.
Your nephew's sister is your niece. Her son is your great nephew. Your nephew's sister might not be related to you if she is the child of a second marriage in which your sibling was not one of the parents. In that case, she is your nephew's half-sister and her son is not related to you either.
your second cousin or nephew or niece
Cousin is neither masculine nor feminine
Your great grandfather's nephew was your grandfather's first cousin. You are two generations removed from your grandfather and his cousin. Therefore you and your great grandfather's nephew are first cousins, twice removed.
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).
Your daughter and your nephew are first cousins. His daughter is your daughter's first cousin, once removed.
Your great grandfather's nephew was your grandfather's first cousin. You are two generations removed from your grandfather and his cousin. Therefore you and your great grandfather's nephew are first cousins, twice removed.
uh you dumb people you mom's cousin's child is your cousin too my mom told me that