Q. Some sources say my brother’s grandchildren are my grandniece and grandnephews. If that’s the case, why am I called a great-aunt? What’s the correct term?
A. Great-aunt or great-uncle is a lot like second cousin: It’s common practice for people to call their grandparents’ siblings by these terms, just as they often refer to first cousins’ children as second cousins—but neither is technically correct. As you noted, the proper term for your relationship to your brother’s grandchildren is grandaunt, just like grandparent. Grand means that the relatives in question are two generations removed from one another.
So aunts and uncles follow the same pattern as parents as you tack on generations:
In case you’re still wondering about cousins: Your first cousins’ children would be your first cousins once removed. See our article “Cousin Confusion.”