You and your mother's brother are first cousins. There is a generation difference between your son and the daughter. That makes them first cousins once removed.
She is your cousin
Mother's grandson as regards her daughter is either her (daughter's) son or her (daughter's) nephew.
Mothers sister is aunt and son is cousin so daughter wouldn't that be a niece
britpaige
the daughter
Your mom's uncle's daughter is your mothers first cousin. Their son would be your second cousin.
You are their aunt or aunt by marriage.
Your father's brother's son is your first cousin and your daughter's second cousin.
Your mums brothers sisters roommate flatmates sisters brothers mothers son.
Your nephew?
Your brother would be your son's daughter's great uncle and your son's daughter would be your brothers great niece! Hopefully that makes sense :)
Perseus was the son of Danae, who was the daughter of King Acrisius of Argos.