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.
First cousins twice removed.
Your brothers great granddaughter is your great great niece.
Your sister's daughter is your niece. Your sister's granddaughter is your great niece Your sister's granddaughter's daughter (your sister's great granddaughter) is your great great niece. You are her great great aunt, if you are a woman, or her great great uncle, if you are a man.
Your son's daughter is your granddaughter. Your sister is your granddaughter's great aunt.
The great great grand daughter would be my cousin sister.
Your aunt is great great aunt to your son's daughter (your granddaughter). Your granddaughter is your aunt's great great niece.
Your niece's daughter is your great niece and her granddaughter is your great great niece. You are the granddaughter's her great great aunt or great great uncle.
You and your wife are great uncle and great aunt to your wife's sister's granddaughter. The granddaughter is your great niece.
My ancestors
Your daughter and your niece are first cousins. Your daughter and your niece's daughter are first cousins, once removed.
Your grandfather's brother is your great uncle. Your great uncle's daughter's daughter (his granddaughter) is your second cousin.
1st cousin 2x removed