Your great aunt is the sister of your grandparent Her son's son is her grandson. Her grandson and you share a great grandparent and thus are Second Cousins to each other.
your cousin
First cousins, twice removed. Aunts daughter is your cousin. Aunts daughters daughter is cousin once removed Aunts daughters daughters daughter is cousin twice removed.
your uncle is your sons great uncle
Your aunt's daughter is your first cousin, and her son is your first cousin, once removed.
great nephew
They would be 3rd cousins.Grandma-GrandpaMom-Auntyou-cousinson-3nd cousinthe diagram is supposed to show that if your cousin has a baby it would be your son's 3rd cousin because your cousin would be his 2nd cousin.
Your mother's aunt's son is her first cousin and your first cousin, once removed.
Your son and your aunt's child are first cousins, so your son and your aunts grandson (the son of your aunt's child) are first cousins, once removed.
Your grandmother's sister is your great aunt, her grand children are your second cousins twice removed. Genetically speaking this is barely a relationship - but if you were raised together as cousins the familiar bond can be tight.
Cousine
Your great aunt's son is your parent's first cousin and your first your cousin, once removed.
Great uncle / Great nephew