5th cousin was the answer first given. This describes the relationship for four generations descended from the first cousins. Therefore it is incorrect. The following explains. The first cousins children, your grandparent's generation, would be second cousins. The second cousin's children, your parent's generation, would be third cousins. Since you are a great-grandchild and you are referring to the great-grandchild of a 1st cousin, you are both of the same generation, the next generation in the lineage. Therefore you are fourth cousins to each other.
Your granddaughter and your first cousin are first cousins, twice removed, to each other.
Your son and your sisters child are first cousins. The granddaughter is out of synch by a generation. That will make them first cousins once removed.
Your 1st cousin's granddaughter would be your daughter's niece.
Some of your granddaughter's first cousins are also your grandchildren, others are not related to you at all.
They are first cousins once removed. Your niece's children and your grandchildren will then be 2nd cousins.
Your son and your first cousin's granddaughter are second cousins, once removed, to each other.
The granddaughter is the niece's first cousin once removed.
Your husband's first cousin's child and your daughter are second cousins to each other.Your husband's first cousin's granddaughter and your daughter are second cousins, once removed, to each other.Your husband's first cousin's granddaughter and yourgrandchild are third cousins to each other.
Your child and your sister's daughter are first cousins. Your grand child and your sister's daughter are first cousins, once removed.
An uncle's nephew and the uncle's child are first cousins to each other. The uncle's great granddaughter and the nephew are first cousins twice removed to each other.
Your grandson and your sister's grandson are second cousins to each other.
Your sister's daughter and your daughter are first cousins to each other. Your sister's daughter's daughter (her granddaughter) is first cousin once removed to you daughter. Your granddaughter and your sister's granddaughter are second cousins to each other.