If the brother of your parent is your uncle, what is the brother of your grandmother or grandfather? This relative is called a grand uncle or great uncle. Genealogy purists like the term grand uncle best because it fits well with the nomenclature for your direct ancestors - grand uncle goes with your grandparent. Similarly, your great-grand uncle is the brother of your great-grand parent. Each generation you go back adds another "great" at the beginning of the name of the relation. In contrast, if you go down the family tree instead of up it, you become the uncle, grand uncle, and great-grand uncle and your relative becomes your nephew/niece, grand nephew/niece, and great-grand nephew/niece.