The Collaborative International Dictionary of English v.0.48:

Lumbering \Lum"ber*ing\, n.
   The business of cutting or getting timber or logs from the
   forest for lumber. [U.S.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Lumber \Lum"ber\, v. t. [imp. & p. p. Lumbered; p. pr. & vb.
   n. Lumbering.]
   1. To heap together in disorder. " Stuff lumbered together."
      --Rymer.
      [1913 Webster]

   2. To fill or encumber with lumber; as, to lumber up a room.
      [1913 Webster]

WordNet (r) 3.0 (2006):

lumbering
    adj 1: slow and laborious because of weight; "the heavy tread of
           tired troops"; "moved with a lumbering sag-bellied trot";
           "ponderous prehistoric beasts"; "a ponderous yawn" [syn:
           heavy, lumbering, ponderous]
    n 1: the trade of cutting or preparing or selling timber

Moby Thesaurus II by Grady Ward, 1.0:

153 Moby Thesaurus words for "lumbering":
   Christmas tree farming, Latinate, afforestation, all thumbs,
   ambling, ambulation, arboriculture, awkward, backpacking,
   blunderheaded, blundering, bombastic, boorish, bulky, bumbling,
   bungling, butterfingered, careless, cautious, circumspect,
   claudicant, clownish, clumsy, clumsy-fisted, cramped, crawling,
   creeping, creeping like snail, cumbersome, cumbrous, deliberate,
   easy, elephantine, faltering, fingers all thumbs, flagging,
   foot-dragging, footing, footing it, footwork, forced,
   forest management, forestation, forestry, formal, fumbling, gauche,
   gawkish, gawky, gentle, going on foot, graceless, gradual, guinde,
   halting, ham-fisted, ham-handed, heavy, heavy-handed, hiking,
   hitchhiking, hitching, hobbled, hobbling, hoofing, hulking, hulky,
   idle, indolent, inelegant, inept, inkhorn, labored, languid,
   languorous, lazy, leaden, left-hand, left-handed, legwork,
   leisurely, limping, logging, loutish, lubberly, lumpish, lumpy,
   maladroit, marching, massive, massy, moderate, oafish,
   pedestrianism, perambulation, poking, poky, pompous, ponderous,
   reforestation, relaxed, reluctant, sauntering, sesquipedalian,
   shuffling, silviculture, slack, sloppy, slothful, slow,
   slow as death, slow as molasses, slow as slow, slow-crawling,
   slow-foot, slow-going, slow-legged, slow-moving, slow-paced,
   slow-poky, slow-running, slow-sailing, slow-stepped, sluggish,
   snail-paced, snaillike, splay, staggering, stiff, stilted,
   strolling, tentative, thumbing, thumbing a ride, toddling,
   tortoiselike, tottering, tramping, treading, tree farming,
   trudging, turgid, turtlelike, uncouth, ungainly, ungraceful,
   unhandy, unhurried, unwieldy, waddling, walking, woodcraft,
   wooden