Your great aunt is either your father or your mother's aunt.
The great aunt is the great niece's baby's great-great aunt.
Your aunt's great grandson is your first cousin twice removed.
second cousin
Your great-aunt
You could be second cousins. Or you could be no relationship at all if they do not share a common ancestor with you.
You Aunt is you grandson's Great-Great Aunt. Your grandson is your Aunt's Great-Great Nephew.
Your great-great aunt is your daughter's great-great-great aunt.
Your great aunt is your daughter's great great aunt. Your daughter is your great aunt's great great niece.
Great Aunt to Great Niece.
you are still are considered an aunt or uncle. But, if you are to introduce them to someone outside the family then you are to be considered their great aunt / uncle
she's also consider a grandmother. Great-aunt actually
Your great aunt's grandson is your second cousin.