From Longman Dictionary of Contemporary Englishmob capˈmob cap noun [countable] DCCa light cotton hat with a decorative edge, worn by women in the 18th and 19th centuries
Examples from the Corpus
mob cap• He needed only a mob cap and frilly apron to complete the image.Origin mob cap (1700-1800) Probably from mab, mob “prostitute, careless dress” ((16-18 centuries)), from the female name Mab, from Mabel 