also cap of dignity or cap of estate
1. : a cap formerly worn as a symbol of office or high rank and still used as the cap of state borne before the British sovereign on certain ceremonial occasions and in modified form as the lining of British royal crowns and peers' coronets
2. : the fur hat worn by the city sword-bearer or borne before the mayor on ceremonial occasions in several cities in England and Ireland
3. : a heraldic cap showing a fur lining turned up about the bottom and split at the back sometimes borne as a charge and often used instead of a wreath to support the crest — called also chapeau