The term 'great cousin' is not one used in genealogy.
You only have great cousins if you have wonderful cousins!
Your great uncle's children are your parent's first cousins and your first cousins once removed.
They would be first cousins once removed. Your great aunt's children are the first cousins of your parent.
You are first cousin, once removed to the children of your great uncle.
Your great great grandmother's sister is your great great aunt. Your and her daughter's common ancestors are your great great great grandparents. The daughter and your great grandmother are first cousins. You and the daughter are first cousins, three times removed.
Your child's children are your grandchildren. Your great uncle's children are your parent's first cousins and your first cousins, once removed. Your grandchildren and your great uncle's children are first cousins, three times removed.
Anyone who has a great grandparent in common will be second cousins. Another way to look at this is to note that the grandchildren of your great aunts and great uncles are your second cousins. Their children are your second cousins, once removed, and their parents are your first cousins once removed.
You don't, simple as that. You could say cousins if it's that important, or "my aunt's nieces and nephews on the other side," but there isn't an actual term for that except your "uncle's wife's siblings children."
First cousins once removed.
One answer:2nd cousins.Another answer:First cousins once removed.Your first cousins are the children of your aunts and uncles.Your children are second cousins to your cousins children.Your children are first cousins once removed to your cousins.
The children of your first cousin are your first cousins once removed. The children of your second cousins are your second cousins once removed And so forth.
Your child and your nephew are first cousins. Your child and your great nephew are first cousins, once removed.
The great grandchildren of your first cousin once removed are your first cousins four times removed.