The Collaborative International Dictionary of English v.0.48:

Ribaudequin \Ri*bau"de*quin\, n. [F.]
   1. An engine of war used in the Middle Ages, consisting of a
      protected elevated staging on wheels, and armed in front
      with pikes. It was (after the 14th century) furnished with
      small cannon.
      [1913 Webster]

   2. A huge bow fixed on the wall of a fortified town for
      casting javelins.
      [1913 Webster] Ribaudred