Pa is an informal, affectionate word for father, similar to papa, pop, or dad. You might hear it in older books or movies, or in certain regions where people still use it regularly. In Little House on the Prairie, Laura Ingalls Wilder always calls her father “Pa,” and he calls her mother “Ma.”

The word has a warm, down-to-earth feeling to it. It suggests closeness and trust, the kind of relationship where a child might say, “Pa, can you help me fix my bike?” or “Pa taught me how to fish.” While fewer families use pa today than a century ago, it's still a perfectly good way to address or refer to your father, especially if it fits your family's style of talking to each other.