Source : Webster's Revised Unabridged Dictionary (1913)

Crossbeam \Cross"beam`\ (-b[=e]m`). n.
   1. (Arch.) A girder.

   2. (Naut.) A beam laid across the bitts, to which the cable
      is fastened when riding at anchor.

Source : WordNet®

crossbeam
     n : a horizontal beam that extends across something [syn: {trave},
          {traverse}, {crosspiece}]