The Collaborative International Dictionary of English v.0.48:

Swag \Swag\, v. i. [imp. & p. p. Swagged; p. pr. & vb. n.
   Swagging.] [Cf. Icel. sveggja, sveigja to bend, to sway,
   Norw. svaga to sway. See Sway.]
   1. To hang or move, as something loose and heavy; to sway; to
      swing. [Prov. Eng.]
      [1913 Webster]

   2. To sink down by its weight; to sag. --Sir H. Wotton.
      [1913 Webster]

            I swag as a fat person's belly swaggeth as he goeth.
                                                  --Palsgrave.
      [1913 Webster]

   3. To tramp carrying a swag. [Australia]
      [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Swag \Swag\, n.
   1. A swaying, irregular motion.
      [1913 Webster]

   2. A burglar's or thief's booty; boodle. [Cant or Slang]
      --Charles Reade.
      [1913 Webster]

   3. [Australia]
      (a) A tramping bushman's luggage, rolled up either in
          canvas or in a blanket so as to form a long bundle,
          and carried on the back or over the shoulder; --
          called also a bluey, or a drum.
      (b) Any bundle of luggage similarly rolled up; hence,
          luggage in general.

                He tramped for years till the swag he bore
                seemed part of himself.           --Lawson.
          [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

swag
    n 1: valuable goods
    2: goods or money obtained illegally [syn: loot, booty,
       pillage, plunder, prize, swag, dirty money]
    3: a bundle containing the personal belongings of a swagman
    v 1: droop, sink, or settle from or as if from pressure or loss
         of tautness [syn: sag, droop, swag, flag]
    2: walk as if unable to control one's movements; "The drunken
       man staggered into the room" [syn: stagger, reel, keel,
       lurch, swag, careen]
    3: sway heavily or unsteadily

Moby Thesaurus II by Grady Ward, 1.0:

190 Moby Thesaurus words for "swag":
   angularity, arch, ascend, bag, bagging, baggy, ballooning, bank,
   bend, bend back, blackmail, bob, bobble, boodle, booty, bow,
   cadence, cant, careen, cascade, catenary, cave, cave in, climb,
   coggle, crook, curl, curve, daggle, dangle, decline, decurrence,
   decurve, deflect, depend, descend, dip, dome, drabble, drag,
   draggle, drape, droop, drooping, droopy, drop, embow, fall,
   fall away, fall off, flag, flap, flex, flop, flop down, floppy,
   flow, fluctuate, flump, flump down, flutter, founder, give way,
   go down, go downhill, go uphill, grade, graft, hang, hang down,
   haul, hook, hot goods, hump, hunch, inclination, incline,
   incurvate, incurve, inflect, keel, lapse, lean, leaning,
   leaning tower, librate, limp, list, loop, loose, loot, lop,
   lop-eared, loppy, lower, lowering, lurch, nod, nodding, nutate,
   oscillate, pend, pendulate, perks, perquisite, pickings, pitch,
   plop, plop down, plump, plunder, pork barrel, prize, public till,
   public trough, rake, recurve, reel, reflect, reflex, resonate,
   retreat, retroflex, rhino, rise, rock, rocks, roll, round, sag,
   sagging, sagging in folds, saggy, scratch, set, settle,
   settle down, shake, shekels, shelve, sidle, sink, sink down,
   sinkage, slant, slope, slouch, slump, slump down, smash, spoil,
   spoils, spoils of office, squeeze, stealings, stolen goods, stuff,
   stumpy, submerge, submergence, subside, subsidence, sugar, sway,
   sweep, swing, swinging, take, till, tilt, tilter, tip, toss,
   tower of Pisa, trail, turn, uprise, vacillate, vault, vibrate, wag,
   waggle, wampum, wave, waver, weep, wilt, wind, wobble, yaw



The Free On-line Dictionary of Computing (30 December 2018):

SWAG

    Scientific (or Silly) Wild Ass Guess.  A term used by
   technical teams when establishing high level sizings for large
   projects.

   (2000-08-09)