dun To badger someone to pay a debt; to importune for payment of a bill; to make repeated and insistent demands; to pester or assail relentlessly. Another term of uncertain origin, dun dates from the 1600s. Tradition has it that a man named Joe Dun, a London bailiff in the reign of Henry VII, was so successful in collecting bad debts that his name became synonymous with the practice of pursuing someone to deliver payment. Dun can also be used in nonfinancial contexts meaning to harass, badger, or plague.