Anonymous

"Great aunt/uncle" is traditional. "Grand" seems more logical, to parallel grandparent, so many people use it. Which one you use might depend on your audience.

Anonymous

the next generation up from parents and uncles and aunts is grandparents granduncles, grandaunts. the generation up from them is the Greats. I don't skip grand for uncles and aunts that I use for parents. That would be confusing, do you not think?

Anonymous

I say great-uncle, great-aunt.

Anonymous

great-uncle/great-aunt

Anonymous

I say great aunt or uncle.