The Collaborative International Dictionary of English v.0.48:

Cantalever \Can"ta*lev`er\, n. [Cant an external angle + lever a
   supporter of the roof timber of a house.] [Written also
   cantaliver and cantilever.]
   1. (Arch.) A bracket to support a balcony, a cornice, or the
      like.
      [1913 Webster]

   2. (Engin.) A projecting beam, truss, or bridge unsupported
      at the outer end; one which overhangs.
      [1913 Webster]

   Cantalever bridge, a bridge in which the principle of the
      cantalever is applied. It is usually a trussed bridge,
      composed of two portions reaching out from opposite banks,
      and supported near the middle of their own length on piers
      which they overhang, thus forming cantalevers which meet
      over the space to be spanned or sustain a third portion,
      to complete the connection.
      [1913 Webster]