[1] : The Collaborative International Dictionary of English v.0.48

plug \plug\, v. t. imp.  p. p. plugged; p. pr.  vb. n.
   plugging.
   to stop with a plug; to make tight by stopping a hole.
   1913 webster

   2. to briefly publicize or advertise, especially during a
      public event not specifically intended for advertising
      purposes; as, during the interview he plugged his new
      book.

   syn: put in a plug for.
        pjc
see also:
plugged plugging 

[2] : The Collaborative International Dictionary of English v.0.48

plug \plug\, n. akin to d. plug, g. pflock, dan. pl"ok, plug,
   sw. plugg; cf. w. ploc.
   1. any piece of wood, metal, or other substance used to stop
      or fill a hole; a stopple.
      1913 webster

   2. a flat oblong cake of pressed tobacco. u. s.
      1913 webster

   3. a high, tapering silk hat. slang, u.s.
      1913 webster

   4. a worthless horse. slang, u.s.
      1913 webster

   5. building a block of wood let into a wall, to afford a
      hold for nails.
      1913 webster

   6. an act of plugging6; a brief mention for the sake of
      publicity or advertisement, especially during a public
      event not specifically intended for advertising purposes;
      as, he put in a plug for his favorite charity.
      pjc

   breech plug gun., in breech-loading guns, the metal plug
      or cylinder which closes the aperture in the breech,
      through which the gun is loaded.

   fire plug, a street hydrant to which hose may be attached.
      u. s.

   hawse plug naut., a plug to stop a hawse hole.

   plug and feather. stone working see feather, n., 7.

   plug centerbit, a centerbit ending in a small cylinder
      instead of a point, so as to follow and enlarge a hole
      previously made, or to form a counterbore around it.

   plug rod steam eng., a rod attached to the beam for
      working the valves, as in the cornish engine.

   plug valve mech., a tapering valve, which turns in a case
      like the plug of a faucet.
      1913 webster
see also:
breech plug fire plug hawse plug plug and feather feather plug centerbit 
plug rod plug valve 

[3] : WordNet (r) 2.0

plug
     n 1: blockage consisting of an object designed to fill a hole
          tightly syn: stopper, stopple
     2: a wad of something chewable as tobacco syn: chew, chaw,
         cud, quid, wad
     3: blatant or sensational promotion syn: ballyhoo, hoopla,
         hype
     4: electrical device that fits into the cylinder head of an
        internal-combustion engine and ignites the gas by means of
        an electric spark syn: spark plug, sparking plug
     5: an electrical device with two or three pins that is inserted
        in a socket to make an electrical connection syn: male
        plug
     6: an upright hydrant for drawing water to use in fighting a
        fire syn: fireplug, fire hydrant
     7: an old or over-worked horse syn: hack, jade, nag
     v 1: fill or close tightly with or as if with a plug; "plug the
          hole"; "stop up the leak" syn: stop up, secure
     2: persist in working hard; "students must plug away at this
        problem" syn: plug away
     3: deliver a quick blow to; "he punched me in the stomach"
        syn: punch
     4: make a plug for; praise the qualities or in order to sell or
        promote
     also: plugging, plugged
see also:
stopper stopple chew chaw cud quid 
wad ballyhoo hoopla hype spark plug 
sparking plug male plug fireplug fire hydrant hack 
jade nag stop up secure plug away 
punch plugging plugged 

[4] : Moby Thesaurus II by Grady Ward, 1.0

253 moby thesaurus words for "plug":
   pr, acknowledgment, advert, advertise, advertisement, advocate,
   appreciation, back, bait, balker, balky horse, ballyhoo, bar, bark,
   bill, bind, birdlime, block, block up, blockade, blurb, bola,
   boost, bright light, build up, buildup, bulletin, bung, caulk,
   cavendish, celebrity, charge, check valve, chew, chink, choke,
   choke off, choke up, chug on, circularize, clog, clog up, close,
   close off, close up, cobweb, cock, commend, commendation,
   commercial, commercial announcement, common knowledge, congest,
   constipate, cork, cover, crock, crowbait, cry, cry up, currency,
   dam, dam up, daylight, detonate, dig, discharge, dog, dragnet,
   drop, drudge, eclat, eject, establish, exposure, fag, fame,
   famousness, faucet, fell, fill, fill up, fire, fire hydrant,
   fire off, fireplug, fishhook, fly, foul, garron, gill net,
   give a write-up, give publicity, glare, goat, good word, grind,
   ground bait, grub, gun, gun for, hack, hammer, hammer away, hit,
   honorable mention, hook, hoopla, hue and cry, hydrant, hype, jade,
   jam, jig, jog on, jughead, keep doggedly at, lariat, lasso,
   let fly, let off, lid, lime, limelight, load, lumber, lure,
   maximum dissemination, mention, meshes, moil, nag, net, noose,
   notoriety, obstipate, obstruct, occlude, pack, peg, peg away, pelt,
   pepper, pick off, pigtail, pin, pistol, placard, plod, plod along,
   plug along, plug at, plug away, plug up, post, post bills, post up,
   pot, potshoot, potshot, pound away, pound net, press notice,
   press-agent, prime, promote, promotion, public eye,
   public knowledge, public relations, public report, publicity,
   publicity story, publicize, publicness, puff, puffing, purse seine,
   push, quid, reclame, recognition, recommend, recommendation,
   report, riddle, roarer, rogue, rosinante, rub on, scalawag, schlep,
   sea cock, seal off, seal up, seine, sell, shoot, shoot at,
   shoot down, slog, slog away, snare, sniggle, snipe,
   speak highly of, speak warmly of, speak well of, spiel, spigot,
   spike, spile, spill, spinner, spot, spot announcement, spotlight,
   springe, squid, stanch, stay, stench, stiff, stop, stop up,
   stopgap, stopper, stopple, strike, stuff, stuff up, stump, support,
   take a potshot, tap, toil, toils, torpedo, tout, tramp, travail,
   trawl, trudge, twist, valve, wad, wade through, water plug,
   whistler, wobbler, work away, write up, write-up

Plug >> P Words
Plug, definition of term: Plug
plug_pag1.html

Plug In >> P Words
Plug In, definition of term: Plug In
plug+in_pag1.html

Plug Hat >> P Words
Plug Hat, definition of term: Plug Hat
plug+hat_pag1.html

Spark Plug >> S Words
Spark Plug, definition of term: Spark Plug
spark+plug_pag1.html

Plug And Play >> P Words
Plug And Play, definition of term: Plug And Play
plug+and+play_pag1.html