He is your second cousin once removed. His children are your third cousins.
nothing
She could be your grandmother. Or she could be your great aunt.
Your grandmother's sisters are your Great Aunts.
If the great grandmother of A is the aunt of B's grandfather, then A and B are third cousins.
Your grandmother's mother is your great grandmother and your son's great-great-grandmother.
Your great grandmother's sister is your great great aunt. Her great grandchild is your third cousin.
Your great grandmother's sister is your great great aunt and your son's great great great-aunt. He is her great great great nephew.
Your great grandparents brothers and sisters are your great uncles and great aunts.
Great neice
You and the granddaughter of your great grandmother's first cousin are third cousins, once removed.
Your grandmother's brother is your great uncle. Your great uncle's grandchildren are your second cousins.
The full form of grandmother is "grand mother," which indicates the position of a mother in relation to one's parents.