The Collaborative International Dictionary of English v.0.48:

Slouch \Slouch\, v. i. [imp. & p. p. Slouched; p. pr. & vb. n.
   Slouching.]
   1. To droop, as the head.
      [1913 Webster]

   2. To walk in a clumsy, lazy manner. [Colloq.]
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Slouch \Slouch\, v. t.
   To cause to hang down; to depress at the side; as, to slouth
   the hat.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Slouch \Slouch\, n. [Cf. Icel. sl?kra slouching felloew, and E.
   slack, slug, a lazy fellow.]
   1. A hanging down of the head; a drooping attitude; a limp
      appearance; an ungainly, clownish gait; a sidewise
      depression or hanging down, as of a hat brim.
      [1913 Webster]

   2. An awkward, heavy, clownish fellow. [Colloq.]
      [1913 Webster]

   Slouth hat, a soft, limp hat of unstiffened cloth or felt.
      [1913 Webster]

WordNet (r) 3.0 (2006):

slouch
    n 1: an incompetent person; usually used in negative
         constructions; "he's no slouch when it comes to baseball"
    2: a stooping carriage in standing and walking
    v 1: assume a drooping posture or carriage [syn: slump,
         slouch]
    2: walk slovenly

Moby Thesaurus II by Grady Ward, 1.0:

237 Moby Thesaurus words for "slouch":
   amble, andante, arm, barge, bay, bayou, bend, blockhead, blunderer,
   blunderhead, bog, boor, botcher, bowl along, bum, bum around,
   bumbler, bundle, bungler, cave, cave in, claudication,
   clock watcher, clod, clodhopper, clodknocker, clot, clown, clump,
   cove, crawl, creek, creep, dallier, dawdle, dawdler, dead march,
   decline, diddler, dillydallier, do nothing, do-nothing, dogtrot,
   dolittle, dolt, doodler, drag, droop, faineant, fen, flop,
   flop down, flounce, flump, flump down, foot, footpace, footslog,
   founder, fumbler, funeral march, gait, gallop, gaum, gawk,
   gentleman of leisure, give way, go down, goldbrick, goldbricker,
   goof off, goof-off, gowk, gulf, halt, hang around, harbor,
   hippety-hop, hitch, hobble, hop, hunch, idle, idleness, idler,
   indolence, jog, jog trot, jolt, jump, klutz, laggard, lapse, laze,
   laziness, lazy, lazybones, lean, leisurely gait, lie around, limp,
   lingerer, loaf, loafer, lobster, lock step, loiter about, loiterer,
   loll, loll around, loller, lollop, lollop around, looby, lop,
   lotus-eater, lough, lounge, lounge around, lounger, lout, lower,
   lubber, lumber, lumbering pace, lump, lunge, lurch, malingerer,
   marsh, marshland, meathead, mince, mincing steps, mire,
   mooch around, moon, moon around, mope, moper, morass, no slouch,
   oaf, ox, pace, paddle, peg, piaffe, piaffer, plod, plop, plop down,
   plump, potterer, prance, putterer, quagmire, rack, roll, sag,
   sashay, saunter, scuff, scuffle, scuttle, set, settle, settle down,
   shamble, shuffle, sidle, single-foot, sink, sink down, sit around,
   skip, slink, slither, slog, slothfulness, slouch around, sloucher,
   slough, sloven, slow march, slow motion, slowness, slubberer, slug,
   slugabed, sluggard, sluggishness, slump, slump down, stagger,
   stalk, stamp, stand around, step, stick-in-the-mud, stomp, stoop,
   straddle, straggle, stride, stroll, strolling gait, strut, stump,
   submerge, subside, sump, swag, swagger, swampland, swing,
   time killer, time waster, tittup, toddle, totter, traipse, tread,
   trifler, trip, trollop, trot, trudge, velocity, waddle,
   waiter on Providence, walk, wamble, wiggle, wilt, wobble, yokel