and then from the internet there's:


There is also no such thing as a great-uncle or great-aunt - the correct term for that is really grand-uncle (like grand-parent) or grand-aunt.


and from a more authoritative-looking site:


Although the term Great Uncle/Aunt is commonly used to describe the brother/sister of a grandparent, the above diagram adopts the preferred term Grand Uncle/Aunt as it properly aligns with the term Grandfather/mother at the same generation. Consequently, we have Great Grand Uncle/Aunt at the same generation as Great Grandfather/mother and so on.



(You're welcome, again).