Word Origin & History
dun (v.)
"to insist on payment of debt," c.1626, perhaps related to dunnen "to sound, resound, make a din," or shortened from dunkirk (1602) "privateer," a private vessel licensed to attack enemy ships during wartime, from Dunkirk, French port from which they sailed. Yet another, less likely, theory traces it to a Joe Dun, supposedly a London bailiff famous for catching defaulters.
[duhn] 
