dun1
  
  adj.
 of a dull greyish-brown colour.
n.
   - a dull greyish-brown colour.
 - a horse with a sandy coat, black mane, tail, and lower legs, and a dark dorsal stripe.
 - a subadult mayfly with drab, opaque wings, or a fishing fly imitating this.
 
 
  Etymology
  OE dun, dunn, of Gmc origin; prob. rel. to dusk.
 
  
    
dun2
  
  v.
 (duns, dunning, dunned)
 make persistent demands on (someone) for payment of a debt.
n.
 archaic a debt collector or an insistent creditor.
 
  Etymology
  C17 (as n.): perh. from obs. Dunkirk privateer (with connotations of piratical demands), or from the name of a Joe Dun, a well-known bailiff.
 
  
    
dun3
  
  n.
 Archaeology  (often in place names) a stone-built fortified settlement in Scotland or Ireland, of a kind built from the late Iron Age to the early Middle Ages.
 
  Etymology
  C18: from Ir. dún, Sc. Gaelic dùn ‘hill or hill fort’.