From the museum's Web site via pinterest.com/mwojdak/17th-century-fashion/.
The Museum’s notes for this…"A late seventeenth-century version of the open robe and one of the earliest costumes in the Museum's collection, this two-piece dress is richly decorated with embroidery in silver-gilt thread. If it looks little like our preconception of eighteenth-century court dress, the anomaly is in part due to a certain sedateness, perhaps more grave than many of the wearer's later Rococo sisters. Moreover, this sensible wool costume is for winter and lacks the deep décolletage and bright silks of spring and summer attire. In 1695, a lady of the French court complained that women were turning blue from the cold when required to wear silk dresses in winter.”
I am taking a risk by not agreeing with the Met, but the style is more Baroque - a period that extended into the early 1700s when it was supplanted by Rococo. In fashion, the close skirts, bustles, and lavish textiles of the late Baroque were replaced by panniers, floral decorations, serpentine ruching, square and U-necklines, and gushing lace in the Rococo. I believe the Museum staff was making a point about how late 1600s-early 1700s (late Louis XIV) dress is nothing like dress in most of the 1700s of Louis XV and XVI.
The silver gilt and train suggest that this dress is meant for a woman of means even if it is not made of opulent silk. The closest analog to this dress on this Site is this print of the comtesse Mailly.
Keywords: British, Fontanges headdress, veil, chemise, high vee neckline, lace cuffs, three quarter length tight sleeves, cuffs, vee waistline, over-skirt, close under-skirt, train, gloves, fan, mantua