aunt or uncle;)
depends on the gender
Second cousin
Your children and your first cousin's children are second cousins. Your children and your second cousin's children are third cousins. And so forth.
Your cousin's sister is also your cousin. Your first cousin's children and you children are second cousins. Your second cousin's children and your children are third cousins. And so forth.
Your 3rd cousin's children are your 3rd cousins once removed.
Your parents are great aunt and great uncle to the children of your first cousin.
Your second cousins.
Your children and the children of your first cousin are second cousins to each other.
Your children and your first cousin are first cousins, once removed, to each other.
Your daughter and your first cousin's children are second cousins to each others.
Your first cousin's son and your children are second cousins to each other. Your second cousin's son and your children are third cousins to each other.
Cousin once removed.
Your children and your first cousin's children are second cousins to each other. Your children and your second cousin's children are third cousins to each other.