The Collaborative International Dictionary of English v.0.48:

Basswood \Bass"wood`\, n. (Bot.)
   The bass (Tilia) or its wood; especially, Tilia
   Americana. See Bass, the lime tree.
   [1913 Webster]

         All the bowls were made of basswood,
         White and polished very smoothly.        --Longfellow.
   [1913 Webster]

WordNet (r) 3.0 (2006):

basswood
    n 1: soft light-colored wood of any of various linden trees;
         used in making crates and boxes and in carving and millwork
         [syn: basswood, linden]
    2: any of various deciduous trees of the genus Tilia with heart-
       shaped leaves and drooping cymose clusters of yellowish often
       fragrant flowers; several yield valuable timber [syn:
       linden, linden tree, basswood, lime, lime tree]