Your mother's brother is your uncle.
Your mother's brother-in-law is your uncle.
you call him your uncle
Your mother's brother is your uncle; you are his niece (if you are a girl) or his nephew (if you are a boy).
Your mother's brother's son is your cousin.
Uncle
Wouldn't that be an uncle.....
they are your cousin
Your mother's mother is your grandmother.
Your mother's brother-in-law is your uncle.
Yes, your mother's mother's brother is commonly referred to as your granduncle or great-uncle. This term denotes the brother of one of your grandparents. Alternatively, you could simply call him your uncle, although that is more commonly used for the brother of your parents.
Your Grand-mother's brother - would be your great-uncle