The English language recognizes no relationship between you and your husband's great uncle.
Your great uncle is the brother of one of your grandparents. If you are a boy, you are your great uncle's great nephew. If you are a girl, you are your great uncle's great niece.
Your great uncle's daughter would be your aunt.
Your Great Uncle is your the brother of one of your grandparents, and therefore the uncle of one of your parents.
Your uncle is your child's great uncle. Your child is his great niece (if a girl) or great nephew (if a boy).
Your grandfather's uncle is your great uncle.
your uncle is your sons great uncle
Your 3rd cousin
Your Grandfather or your Great Uncle.
great great uncle
Your uncle's great granddaughter is your first cousin, twice removed.
His great uncle
You are her great-aunt/uncle. She is your great-niece.