What is the definition of an "Appalachian Hollow (Holler)"?

Answer 1

A hollow [and, holler is just fine also] is technically a "drainage" - it's a small valley that is usually wooded, often has a creek for water, and offers security from the elements and in older times from attack.

It is common for hollows to have a cave higher up - a great place of refuge if necessary.

Answer 2

well I think it is an old country road. Like a street, but it is very country like, and its old. I live up a holler, and its just a rural country like place that has been here for a long time, where people live.