This depends whether he is your second cousin's sibling'schild or your second cousin's spouse's sibling's child.
It depends.
If the second cousin's neice's parent is your second cousin's sibling, she is your second cousin once removed.
However, if the second cousin's neice's parent is only your second cousin's sibling's spouse or partner, she can only be described as your second cousin's neice.
Your niece and your second cousin are second cousins, once removed, to each other - unless they are from different sides of your family. In that case they would not be related at all.
That could depend on the exact relationship, which is not clear. They could be third cousins, if they share a common Great Great Grandparent. Otherwise there is no relationship.
Your child and your great nephew's parents would be first cousins. Their children would then be second cousins. And if they have children, they will be third cousins.
Your son and your nephew are First Cousins. The children of your nephew and the children of your son are Second Cousins to each other.
Your uncle's grandchildren are your first cousins, once removed. They and your grand children are your second cousins, 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.
Your nephew and your daughter are first cousins to each other. Your nephew's son and your daughter are first cousins, once removed. Your nephew's son and your daughter's child would be second cousins to each other.
A great great grandchild and a great great nephew of the same person are third cousins, once removed.
cousins.
Your child and your nephew are first cousins. Your child and your great nephew are first cousins, once removed.
First cousins once removed. Your child and your nephew are first cousins and there is one generation difference.
Your son and your mother's sister are in a "Great Nephew/Great Aunt" relationship.
Your nephew and your daughter are first cousins to each other.Your nephew's son and your daughter are first cousins, once removed, to each other.