It depends whether you are a boy or a girl. If you are a boy you are his nephew; a girl his niece.
Your great uncle
Your daughter is your uncle's grand niece.
Your Uncle's son is your first cousin.
Your grandfather's brother is your great uncle and your parent's uncle.
You grandson is great great nephew to your uncle. You uncle is great great uncle to your grandson
You grandson is great great nephew to your uncle. You uncle is great great uncle to your grandson
uncle
Yes, he is their great uncle.
He would be his great great great uncle
You and your uncle's grandson are first cousins once removed.
Your great uncle's grandchild is your second cousin.
Your uncle's granddaughter and your child are second cousins.