I think this is a 1920's Women's Suit. It's an odd piece - maybe even a costume from a later period. But the zipper is very very old, and a side zip. I have other pieces from this period that have zippers too. But the clincher is that the piece has a dropped waist and very old hooks on the interior of the belt. The belt doesn't ride on the waist, it actually rides on the hips and the buttons were swapped out later. So, that's my guess.