You and your first cousin's daughter are first cousins, once removed, to each other.
Your wife's brother is your brother-in-law. His son's daughter is his granddaughter and your child's first cousin, once removed, but is not related to you. You can refer to her as "my brother-in-law's granddaughter."
If you are a woman, you are your great grandmother's great granddaughter so your son is the son of her great granddaughter. But there are other possible relationships to other of her great granddaughters.The great granddaughter could be your sister. Then your son is her nephew and she is his aunt.The great granddaughter could be your first cousin. Then she and your son are first cousins, once removed.The great granddaughter could be your second cousin. Then she and your son are second cousins, once removed.
. Your uncle is one of your parents brother. His son or daughter is your cousin. The granddaughter is a second cousin.
Your mothers sisters Granddaughter is your second cousin
Your granddaughter could be your son's daughter, or your son's niece.
Your grandfather's son is either your father or your uncle. Your daughter's grandfather is your father. or your father-in-law.So your daughter's grandfather is your grandfather's son or a brother if there is more tha one son, or, as your father-in-law, is not related to your grandfather's son at all.
Your granddaughter and your niece's son (the grandson of one of your siblings) are second cousins to each other.
Your granddaughter and your niece's son are second cousins.
Your son's daughter is your granddaughter. Your sister is your granddaughter's great aunt.
Your uncle's son is your first cousin.
Yes, your grandfather's granddaughter could be your sister, making her son your nephew.
You would call your father's brother's granddaughter's son your second cousin. In family terms, your father's brother is your uncle, his granddaughter is your cousin, and her son is your second cousin.