* Tante: This is the most common and general term for aunt. It's used for the sister of your parent, as well as for the wife of your uncle.
* Suster: This literally means "sister" and is used for your mother's sister.
* Skouster: This means "sister-in-law" and is used for your father's sister.
* Tante [name]: You can also address your aunt by her first name, preceded by "Tante".
So, depending on the context, you can use any of these options.