The Collaborative International Dictionary of English v.0.48:

Lightwood \Light"wood`\ (l[imac]t"w[oo^]d`), n.
   Pine wood abounding in pitch, used for torches in the
   Southern United States; pine knots, dry sticks, and the like,
   for kindling a fire quickly or making a blaze.
   [1913 Webster]

WordNet (r) 3.0 (2006):

lightwood
    n 1: tall Australian acacia yielding highly valued black timber
         [syn: lightwood, Acacia melanoxylon]