The Collaborative International Dictionary of English v.0.48:

Radeau \Ra`deau"\ (r[.a]`d[=o]"), n. [F.]
   A float; a raft.
   [1913 Webster]

         Three vessels under sail, and one at anchor, above
         Split Rock, and behind it the radeau Thunderer. --W.
                                                  Irving.
   [1913 Webster]