The Collaborative International Dictionary of English v.0.48:

Whitewood \White"wood`\, n.
   The soft and easily-worked wood of the tulip tree
   (Liriodendron tulipifera). It is much used in cabinetwork,
   carriage building, etc.
   [1913 Webster]

   Note: Several other kinds of light-colored wood are called
         whitewood in various countries, as the wood of
         Bignonia leucoxylon in the West Indies, of
         Pittosporum bicolor in Tasmania, etc.
         [1913 Webster]

   Whitewood bark. See the Note under Canella.
      [1913 Webster]