derby (n.)

type of hat," manufactured in U.S. 1850, name appears 1870, perhaps from annual Derby horse race in England, where this type of hat was worn. Race was begun 1780 by the 12th Earl of Derby; the name was used for any major horse race after 1875. Derby the English shire is Old English Deorby "deer village," from deor "deer" + by "habitation, homestead," from a Scandinavian source (see bylaw).