The Collaborative International Dictionary of English v.0.48:

Junk \Junk\ (j[u^][ng]k), n.
   A fragment of any solid substance; a thick piece. See
   Chunk. [Colloq.] --Lowell.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Junk \Junk\, n. [Pg. junco junk, rush, L. juncus a bulrush, of
   which ropes were made in early ages. Cf. Junket.]
   [1913 Webster]
   1. Pieces of old cable or old cordage, used for making
      gaskets, mats, swabs, etc., and when picked to pieces,
      forming oakum for filling the seams of ships.
      [1913 Webster]

   2. Old iron, or other metal, glass, paper, etc., bought and
      sold by junk dealers.
      [1913 Webster]

   3. Hence: Something worthless, or only worth its value as
      recyclable scrap.
      [PJC]

   4. (Naut.) Hard salted beef supplied to ships.
      [1913 Webster]

   Junk bottle, a stout bottle made of thick dark-colored
      glass.

   Junk dealer, a dealer in old cordage, old metal, glass,
      etc.

   Junk hook (Whaling), a hook for hauling heavy pieces of
      blubber on deck.

   Junk ring.
      (a) A packing of soft material round the piston of a steam
          engine.
      (b) A metallic ring for retaining a piston packing in
          place;
      (c) A follower.

   Junk shop, a shop where old cordage, and ship's tackle, old
      iron, old bottles, old paper, etc., are kept for sale.

   Junk vat (Leather Manuf.), a large vat into which spent tan
      liquor or ooze is pumped.

   Junk wad (Mil.), a wad used in proving cannon; also used in
      firing hot shot.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Junk \Junk\, n. [Pg. junco; cf. Jav. & Malay jong, ajong, Chin.
   chwan.] (Naut.)
   A large vessel, without keel or prominent stem, and with huge
   masts in one piece, used by the Chinese, Japanese, Siamese,
   Malays, etc., in navigating their waters.
   [1913 Webster]

WordNet (r) 3.0 (2006):

junk
    n 1: the remains of something that has been destroyed or broken
         up [syn: debris, dust, junk, rubble, detritus]
    2: any of various Chinese boats with a high poop and lugsails
    v 1: dispose of (something useless or old); "trash these old
         chairs"; "junk an old car"; "scrap your old computer" [syn:
         trash, junk, scrap]

Moby Thesaurus II by Grady Ward, 1.0:

270 Moby Thesaurus words for "junk":
   Amytal, Amytal pill, Demerol, Dolophine, H, Luminal, Luminal pill,
   M, Mickey Finn, NG, Nembutal, Nembutal pill, Seconal, Seconal pill,
   Tuinal, Tuinal pill, addictive drug, alcohol, amobarbital sodium,
   analgesic, anodyne, barb, barbiturate, barbiturate pill, bark,
   bawley, bilander, black stuff, blue, blue angel, blue devil,
   blue heaven, blue velvet, boot out, bounce, brig, brigantine,
   bully, buss, calmative, candy, caravel, cashier, cast, cast aside,
   cast out, castaway, castoff, cat, catamaran, cheap, cheat,
   chloral hydrate, chuck out, clamjamfry, clinquant, clipper,
   codeine, codeine cough syrup, collateral, corsair, corvette,
   counterfeit, cutter, dandy, dangerous drug, debris, defenestrate,
   depressant, depressor, derelict, detrude, dhow, discard, discharge,
   dogie, dolly, dope, downer, dromond, drug, dummy, dust, eject,
   exclude, expel, extrude, fake, fakement, fishing smack, flattie,
   flotsam, flotsam and jetsam, forgery, foundling, four-masted bark,
   four-master, frame-up, fraud, frigate, galiot, galleass, galleon,
   garbage, give the hook, good-for-naught, good-for-nothing,
   goofball, hard drug, hard stuff, heave out, heroin, hoax, hooker,
   hop, horse, hoy, hypnotic, ice yacht, imitation, impostor, jetsam,
   jettison, junky, keelboat, kelter, ketch, kick downstairs,
   kick out, knockabout, knockout drops, lagan, lateen, lateener,
   laudanum, liquor, litter, lorcha, lotus, lugger, lumber,
   meperidine, methadone, mock, morphia, morphine, narcotic,
   no-account, no-good, nobby, not worth having, not worth mentioning,
   not worthwhile, nugacious, nugatory, obtrude, ocean racer, offal,
   opiate, opium, orphan, oust, outrigger, pacifier, pain killer,
   paregoric, paste, pen yan, pension off, phenobarbital,
   phenobarbital sodium, phony, pilot boat, pinchbeck, pinnace,
   piragua, pirogue, pram, pungy, purple heart, put out, put-on,
   put-up job, quietener, racing yacht, raff, rainbow, red, refuse,
   reject, remove, retire, riffraff, rigger, rip-off, rubbish, rubble,
   sailing auxiliary, sailing canoe, sailing dinghy, sailing packet,
   sailing trawler, sampan, sandbagger, scag, schooner, scooter,
   scrap, secobarbital sodium, sedative, shabby, shallop, sham,
   sharpie, shipentine, shit, shoddy, simulacrum, skipjack,
   sleep-inducer, sleeper, sleeping draught, sleeping pill, sloop,
   slough, smack, smack boat, snow, sodium thiopental, somnifacient,
   soother, soothing syrup, soporific, stuff, superannuate, swindle,
   tar, tartan, throw away, throw out, throw overboard, thrust out,
   tinsel, topsail schooner, toss out, tranquilizer, trash, trashy,
   trimaran, trivial, truck, turn out, turps, valueless, waif,
   waifs and strays, wash out, waste, wastrel, well smack, whaler,
   white stuff, whited sepulcher, wool-clipper, worthless, xebec,
   yacht, yawl, yellow, yellow jacket