Your first cousin's child is your child's second cousin.
Your second cousin's child is your child's third cousin.
Your third cousin's child is your child's fourth cousin.
and so forth
Your child and your first cousin's child are second cousins to each other.
Your child and your second cousin's child are third cousins to each other.
Your child and your third cousin's child are fourth cousins to each other.
And so forth.
Your child and your 1st cousin are 1st cousins once removed.
Your child and your first cousin are first cousins once removed.
This is if the cousin is your first cousin. They would be your first cousin once removed. Since the child of your cousin is a generation away from you they are the once removed.
Since I am probably not related to you, your child is probably not related to my cousin.
Your niece or nephew...
Your first cousin's child is your first cousin once removed.
Second cousin.
The child of your father's first cousin is your second cousin.
isn't it second cousin?.
first cousin twice removed
The relationship between your sister's (or brother's) child and your cousin is the same as the relationship between your child and your cousin. Your child and your first cousin are first cousins, once removed. Your child and your second cousin are second cousins, once removed, and so forth.
Your second cousin's child is your second cousin, once removed. Your second cousin's child and your child are third cousins to each other.
The child of your first cousin is your first cousin, once removed.Your child and the child of your first cousin are second cousins to each other.
Your son and your 1st cousin's child are 2nd cousins.
Your child and your first cousin's child are second cousins. Your child and your second cousin's child are third cousins to each other.
He is your nephew and you are his uncle.
The child of your first cousin, once removed, is your first cousin, twice removed.