They'd be your cousin.
First cousins, twice removed. Aunts daughter is your cousin. Aunts daughters daughter is cousin once removed Aunts daughters daughters daughter is cousin twice removed.
the daughter's cousin
Granddaughter
Your grandson.
You call your daughter's baby, your grand-duaghter.
You would call your sister's daughter your niece.
Your aunt's daughter is your first cousin.
Your grandson.
Eminem has only been married to one woman, Kimberly Scott.
They would be your second cousin. Your great aunt is the sister of one of your grandparents. Your parents and the granddaughter's parents are first cousins.
Your grand daughter's husband is your grandson-in-law.
Your niece's daughter is your grand niece, or, as some would say, your great niece.