The Collaborative International Dictionary of English v.0.48:

Midden \Mid"den\, n. [Also midding.] [Cf. Dan. m["o]gdynge, E.
   muck, and dung.]
   [1913 Webster]
   1. A dunghill. [Prov. Eng.]
      [1913 Webster]

   2. An accumulation of refuse about a dwelling place;
      especially, an accumulation of shells or of cinders,
      bones, and other refuse on the supposed site of the
      dwelling places of prehistoric tribes, -- as on the shores
      of the Baltic Sea and in many other places. See Kitchen
      middens.
      [1913 Webster]

WordNet (r) 3.0 (2006):

midden
    n 1: (archeology) a mound of domestic refuse containing shells
         and animal bones marking the site of a prehistoric
         settlement [syn: eitchen midden, midden, kitchen
         midden]
    2: a heap of dung or refuse [syn: dunghill, midden,
       muckheap, muckhill]