Your mother's sister is your Aunt. You are her niece or nephew.
cousin
Mom
In Hindi, you would call your mother's sister "mausi" or "masi".
Our cousins are our mothers sisters son :)
His relationship to you is brother-in-law.
Your mothers sister is your Aunt
Mothers sister is aunt and son is cousin so daughter wouldn't that be a niece
A gatecrasher.
In Arabic, you would refer to your mother's sister as "خالة" (khala).
You could call them as a brother/sister or as a cousin... If you're asking for yourself then good luck with that family.
Her sister was named Aga.
The child of your mother's sister is your first cousin.