She would be his Great Aunt
Mother's grandson as regards her daughter is either her (daughter's) son or her (daughter's) nephew.
The son of your Uncle's son is your uncle's grandson. Your uncle's grandson is your first cousin, once removed.
Your great grandparents brothers and sisters are your great uncles and great aunts.
Tutankhamun was the great-grandson of Thutmose II. Thutmose II was the father of Hatshepsut and the grandfather of Tutankhamun through his daughter, who married Amenhotep III, Tutankhamun's grandfather. Thus, their relationship is that of great-grandfather to great-grandson.
The grandson of your first cousin and your grandson are third cousins to eachother.
nothing
Your sister's son is her grandson and your great nephew. Some use the term "grand nephew."
There is no relation between you and your grandmother's cousin-in-law's grandson.
Your father's great grandson could be your grandson, or your great nephew.
You and your uncle's grandson are first cousins once removed.
Your grandson is your sister's great nephew and she is his great aunt.
You grandson is great great nephew to your uncle. You uncle is great great uncle to your grandson
You grandson is great great nephew to your uncle. You uncle is great great uncle to your grandson
The grandchildren of siblings are second cousins to each other.
Your grandson and your great nephew are second cousins to each other.
Second cousin.
Great Grand Nephew