WordNet (r) 3.0 (2006):

softwood
    n 1: wood that is easy to saw (from conifers such as pine or
         fir) [syn: softwood, deal]

Moby Thesaurus II by Grady Ward, 1.0:

71 Moby Thesaurus words for "softwood":
   arborary, arboreal, arboreous, arborescent, arboresque, arborical,
   arboriform, beam, billet, board, boarding, bushlike, bushy,
   citrous, clapboard, coniferous, cord, cordwood, deal, deciduous,
   dendriform, dendritic, dendroid, driftwood, evergreen, firewood,
   hardwood, lath, lathing, lathwork, log, lumber, nondeciduous,
   panelboard, paneling, panelwork, piny, plank, planking, plyboard,
   plywood, pole, post, puncheon, scrubbly, scrubby, scrublike, shake,
   sheathing, sheathing board, sheeting, shingle, shrubby, shrublike,
   sideboard, siding, slab, slat, splat, stave, stick, stick of wood,
   stovewood, three-by-four, timber, timbering, timberwork, treelike,
   two-by-four, weatherboard, wood