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The Met, Robe a la Polonaise, 1787: This popular style was named for the division of Poland into three parts in 1772, symbolized by the three portions of the skirt, when drawn up. The Robe a la Polonaise also features a cutaway bodice styled like a man's frock coat, and worn over a gilet, or vest. There is no waist seam, and the bodice hangs loosely from the center front. The Robe a la Polonaise was in fashion in the 1770s and 1780s.
Too bright and shiny, and a bit too late in the period, but maybe a good place to start -- 18th Century Robe a la Francais in by HandBoundCostumes on Etsy