Your father's sister's daughter is your cousin. Therefore, your father's sister's daughter's daughter would be your cousin's daughter. In genealogical terms, she would be your first cousin once removed.
Your sister's daughter is your niece. If you are a woman, you are your niece's aunt; if you are a man, you are your niece's uncle. Your sister's son is your nephew.
the daughter's cousin
your second cousin
You would call your sister's daughter your niece.
I think you mean "what do you call my father's sister's daughter?"She would be your 1st cousin and your fathers niece.___________________________________________________________Niece by definition is the daughter of one's brother, sister, brother-in-law, or sister-in-law. WhileCousin is by definition the son/daughter of your uncle or aunt.Accordingly, the daughter of the sister of your father is your cousinRefer to link below
To your sister's daughter you are an aunt (or uncle) and she is your niece. To your niece's daughter ( your sister's granddaughter) you are a great-aunt (or great-uncle) and she is your grand-niece.
They are second cousins
Your brother or sister's daughter is called 'your niece.'
Evelyn had her fathers baby making the baby both sister and daughter
She is your niece, you are her aunt or uncle.
Your sister's daughter is your niece.
Your daughter's daughter is your grand daughter. Your nephew's daughter is the granddaughter of your sibling (your brother or sister) The grandchildren of siblings are second cousins.