Definition of "understocking"

On the 1st of February of 1715 I received the dues of La Cañada, three bushels of wheat; eight sacks and a half of maize; some cotton-thread understockings worth 3 pesos, and two pairs of gloves;

1948, New Mexico Historical Review, page 211

As white understockings, which may easily have been completely hidden, also occur, it is possible that the well-dressed man often wore three pairs of stockings. Roelof de Man — always a standard of elegance in Cape terms — had twelve pairs of white understockings and fourteen pairs of overstockings, including examples in green Naples silk, pearl-coloured English silk, ash-grey wool (sajet), black English silk, red serge, and white linen. While Ensign [Pieter] Evriard runs him a close second with five pairs of white understockings and thirteen pairs of overstockings in a rather similar range of colours and materials.

1982, Africana Notes and News, volume 25, page 163

He [Jeremias van Rensselaer] may have worn understockings to protect the outer pair from sweat and foot odors; in the 1650s, overstockings or ‘canons,’ which were widened and decorated at the top, better fitted the wider boots worn by men at this time.

2003, Janny Venema, “The Van Rensselaers as commercial entrepreneurs”, in Beverwijck: A Dutch Village on the American Frontier, 1652–1664, Hilversum: Verloren; Albany, N.Y.: State University of New York Press, section “Place in the community; Life style”, subsection “Outer appearance: Clothing”, page 215