Your cousin's daughter is called your first cousin, once removed. Although the term "second cousin" is sometimes used for this relationship, it is technically incorrect.
Your first cousin's daughter is your first cousin, once removed.
Second cousins
Your sister's daughter and your son are first cousins to each other.
Cousins
Your sister's daughter and your daughter are first cousins to each other. Your sister's daughter's daughter (her granddaughter) is first cousin once removed to you daughter. Your granddaughter and your sister's granddaughter are second cousins to each other.
Your cousin's daughter is your first cousin once removed. Your daughter and your cousin's daughter would be second cousins.
They would be cousins.
Your relationship would be that of cousins.
Your nephew and your daughter are first cousins.
You are First Cousins
You are cousins
Your great uncle's kids are your parent's first cousins. His grandchildren are your second cousins.
Your daughter and your niece are first cousins Your daughter and your great grand niece are first cousins, twice removed.