berm /ˈbɝm/
  城牆與外濠間之狹路
  Berm Berme  n.
  1. Fort. A narrow shelf or path between the bottom of a parapet and the ditch.
  2. Engineering A ledge at the bottom of a bank or cutting, to catch earth that may roll down the slope, or to strengthen the bank.
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  berm
       n 1: a narrow ledge or shelf typically at the top or bottom of a
            slope
       2: narrow edge of land (usually unpaved) along the side of a
          road [syn: shoulder]