A quick definition of matertera:

Term: Matertera

Definition: A matertera is a special kind of aunt. She is your mother's sister.

In ancient Rome, the law recognized the importance of family relationships. The term "matertera" comes from Latin and was used to describe the maternal aunt. This means that she is related to you through your mother's side of the family.

So, if you have a matertera, she is your aunt who is your mother's sister. She is a special member of your family who loves and cares for you just like any other aunt would.