Your grandfather's first cousin is your first cousin, twice removed. His second cousin is your second cousin, twice removed.
cousin
3rd cousin
Your grandfather's niece is a first cousin of one of your parents. Her son is your second cousin.
Your grandmother is first cousins with cousin. Your parent would be the second cousin of the cousin's son. That would make you second cousins once removed.
Your cousin's cousin could either be your cousin or no relation at all.
Your grandfather's cousin is your cousin twice removed. Her husband has no direct relationship to you.
He is of relation as a cousin-in-law.
Your grandfather's sister is your great aunt.
Well, your cousin's brother is also your cousin, and a cousin's son is also your cousin.
Your great great grandfather.
Your grandfather's great nephew is your second cousin.
Your cousin. You are that person's second cousin.