The Collaborative International Dictionary of English v.0.48:

Linden \Lin"den\ (l[i^]n"den), n. [Orig. an adj. from lind
   linden tree, AS. lind; akin to D. & G. linde, OHG. linta,
   Icel., Sw., & Dan. lind. Cf. Lime linden.] (Bot.)
   (a) A handsome tree (Tilia Europ[ae]a), having cymes of
       light yellow flowers, and large cordate leaves. The tree
       is common in Europe.
   (b) In America, the basswood, or Tilia Americana.
       [1913 Webster]

WordNet (r) 3.0 (2006):

linden
    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]