Your second cousin and your grandson are second cousins, twice removed.
2nd cousin once removed
2nd cousin, but if it's your Dad's 2nd cousin... then your relationship with that cousin would be a 3rd cousin.
Your father's first cousin's child is your second cousin. Your father's first cousin's grandchild is your second cousin, once removed. Your child and your father's first cousin's grandchild are third cousins to each other.
Your nephew is the son of your sibling and a first cousin of your childrenYour grand nephew (or great nephew) is the grandson of your sibling and a second cousin of your grandsonYour great great nephew (or great grand nephew) is the great grandson of your sibling and is a 2nd cousin once removed of your grandson
2nd cousin
He\she is your 2nd cousin.
Your son and your 1st cousin's child are 2nd cousins.
You and your father's cousin's granddaughter are 2nd cousins once removed.
2nd cousin
2nd cousin.
2nd Cousin
Yes, you share a common great-grandparent.