A mobcap (or mob cap or mob-cap) is a round, gathered or pleated cloth (usually linen) bonnet consisting of a caul to cover the hair, a frilled or ruffled brim, and (often) a ribbon band, worn by married women in the 18th and early 19th centuries, when it was called a "bonnet". These caps were always gathered to a flat, often curved, brim. The caul had a flat bottom and curved top. The bottom was typically gathered to fit the back neck with a drawstring, while the curved sides and top were tightly gathered and stitched to the brim, which typically had some curves, too. Originally an informal style, the bonnet became a high-fashion item as part of the adoption of simple "country" clothing in the later 18th century. It was an indoor fashion, and was worn under a hat for outdoor wear.