The daughter of your brother or sister is your niece.
The son or daughter of a parents sibling is you cousin.
A brother or a sister who ain't your siblings.
Cousin.
you can call him your nephew if you are mom's daughter's sibling or if you will be the mom you can call him your grandson.
You would call your daughter's son by his name ex: Hi Jack.
The English language has no term to describe a relationship between you and the parents of your daughter-in-law. In English-speaking cultures, you are not related. If you have to refer to them other than by name, you can call them "my son's parent's-in-law" or "my daughter-in-law's parents."
The son of either your sister or your brother is your nephew. The English language does not make a distinction in that.
His name.
The son of your parents is your brother.
Your daughter is your sister's niece. Your daughter's son is her great nephew.
daughter...daughter in law.
Sometimes its because the parents don't want their son or daughter calling all the time and bothering the other parents.
Your grandson.
Yes. Any son or daughter of Zeus would be her half-sibling. Any son or daughter of Poseidon or Hades would be her cousin as Poseidon and Hades are her uncles.
Your niece.Your brother's daughter would be your niece and you'd be her uncle or aunt. Your sister's daughter would also be your niece. If your sibling had a son, he would be your nephew.