While some people prefer the terms grand aunt or grand uncle, parallel to grandmother or grandfather, the terms great aunt and great uncle are widely used and accepted, and are functionally the same.
Your great aunt is the sister of one of your grandparents, which makes you a grand niece or grand nephew (great niece or great nephew). The son of said grand aunt is a first cousin of one of your parents. The son's daughter is first cousin once removed to your parent, and second cousin to you.
Great Niece.
She would be your great grandmother
Your aunt's daughter is your first cousin, and her son is your first cousin, once removed.
The relationship to you would be your cousin !
your cousin
Cousine
It's called the daughter-in-law.
i am my own grandfather
They are second cousins
aunts, cousins, daughters, sons, and friend.
Your son and your nephew are first cousins to each other. Their daughters are second cousins to each other.
Elvis, you "Cannot William Shatner impersonater." your great niece.