. Your uncle is one of your parents brother. His son or daughter is your cousin. The granddaughter is a second cousin.
Your great uncle's granddaughter is your second cousin.
You mother's uncle's granddaughter is your second cousin.
Your uncle's granddaughter and your child are second cousins.
If your great great uncle (the brother of your great grandparent) had a great great granddaughter, you would be third cousins, once removed.
The mother of your uncle (by marriage) is not related to you. Neither are any of her other descendants or relations.
Your uncle's great granddaughter is your first cousin, twice removed.
Your nephew's granddaughter is your great great niece. Depending on whether you are male or female, you are that child's great great uncle or great great aunt.
Your grandmother's brother is your great uncle. Your great uncle's son's great granddaughter is your great uncle's great great granddaughter. Your great uncle's great great granddaughter is your second cousin, twice removed, and is your daughter's third cousin, once removed.
Your grandfather's brother is your great uncle. Your great uncle's daughter's daughter (his granddaughter) is your second cousin.
Your granddaughter could be your son's daughter, or your son's niece.
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.
You are the great-great-aunt/uncle to your niece's granddaughter. This means that your niece's granddaughter is your great-great-niece. The term "great-great" signifies that there are two generations between you and your niece's granddaughter.