This literally translates to "mother's father" as it refers to the father of your mother's sibling.
Here's why this term is used:
* Filipino culture emphasizes the importance of family ties. Even though the stepfather is not biologically related, the term highlights the connection through the mother's side.
* There is no single word equivalent to "stepfather" in Filipino. The phrase "ama ng tiyahin" is the most common and widely understood way to refer to a stepfather.
While "ama ng tiyahin" is the most accurate translation, you can also use "ama-amahan" which translates to "father-like" or "father figure." This is a more informal and less literal way to refer to a stepfather.
It's always best to consider the specific context and relationship when choosing how to refer to someone's stepfather in Filipino.