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.
Yes if you will mean that uncles posses something. Examples: uncles' houses (the houses of uncles) uncles' children (the children of uncles)
Cousin. Your parents brothers and sisters are aunts and uncles. and the aunt and uncles children are your cousins.
aunties and uncles
cousin
They are your cousins.
Your grandfather's children are either your parents or aunts or uncles.
Your aunt is your child's Great Aunt, so your child is her great niece or great nephew.
Cousins are the children of of both your parent's siblings (your aunts or uncles.)
Your brother or sister are your siblings. Your cousins are the children of your aunts and uncles.
I believe they would be great aunts or great uncles.
great great (etc.) grandparents great grandparents grandparents + great uncles and great aunts parents + uncles and aunts [=parents' siblings] siblings + cousins [=uncles' and aunts' children] children + nephews and nieces [=siblings' children] grandchildren great gandchildren great great (etc.) grandhildren also cousins and second cousins [=(great-)grandparents' descendants]
great great (etc.) grandparents great grandparents grandparents + great uncles and great aunts parents + uncles and aunts [=parents' siblings] siblings + cousins [=uncles' and aunts' children] children + nephews and nieces [=siblings' children] grandchildren great gandchildren great great (etc.) grandhildren also cousins and second cousins [=(great-)grandparents' descendants]