Small valleys or low-lying areas of land, often shaded and surrounded by hills; or empty spaces inside something.
From Old English 'hol' (hole) plus 'ow' suffix. Used since medieval times for both geographical and physical empty spaces.
Appalachian 'hollows' are celebrated in literature and music as places of cultural pride—Appalachian folk songs and stories often name specific hollows, making them characters in their own right.
Complete word intelligence in one call. Free tier — 50 lookups/day.