[1] : WordNet (r) 2.0

shut up
     adj : closely confined syn: pent, shut upp
     v 1: refuse to talk or stop talking; fall silent; "the children
          shut up when their father approached" syn: close up,
          clam up, dummy up, belt up, button up, be quiet,
           keep mum ant: open up
     2: place in a place where something cannot be removed or
        someone cannot escape; "the parents locked her daughter up
        for the weekend"; "she locked her jewels in the safe"
        syn: lock in, lock away, lock, put away, shut
        away, lock up
     3: cause to be quiet or not talk; "please silence the children
        in the church" syn: hush, quieten, silence, still,
         hush up ant: louden
see also:
pent shut upp close up clam up dummy up belt up 
button up be quiet keep mum open up lock in 
lock away lock put away shut away lock up 
hush quieten silence still hush up 
louden 

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

177 moby thesaurus words for "shut up":
   anchoritic, answer, answer conclusively, argue down, bang, bar,
   barricade, batten, batten down, be mute, be silent, beleaguer,
   beset, besiege, blockade, bolt, bottle up, bound, box in, box up,
   button, button up, cage, cease, chamber, check, choke, choke off,
   clap, cloister, cloistered, close, close down, close in,
   close shop, close up, compass, confine, confound, confute,
   constrain, constrict, contain, contract, contradict, controvert,
   coop, coop in, coop up, cordon, cordon off, cork up, corral, cover,
   crib, crush, defeat, demolish, deny, detain, dismiss, dispose of,
   domestic, dry up, dummy up, encage, encircle, enclose, encompass,
   enshrine, eremitic, fasten, fence in, finish, floor, fold, fold up,
   forswear speech, hedge in, hem in, hermitic, hermitish, hold,
   hold in custody, hold in restraint, house in, hush, immure,
   impound, imprison, incarcerate, include, inhibit, jail, keep in,
   keep in custody, keep in detention, keep mum, keep quiet,
   keep silent, keep still, kennel, key, latch, leaguer, lock,
   lock out, lock up, make no sign, mew, mew up, nonplus, occlude,
   overthrow, overturn, overwhelm, padlock, parry, pen, pen in,
   pen up, pipe down, play dumb, plumb, pocket, pound, put to silence,
   quarantine, quiet, quiet down, quieten, rail in, rebut, recluse,
   reduce to silence, refute, restrain, restrict, say nothing, seal,
   seal off, seal up, secure, sequestered, settle, shackle, shrine,
   shush, shut, shut down, shut in, shut the door, shut up shop,
   shutter, silence, slam, smash all opposition, snap, soft-pedal,
   squash, squeeze shut, squelch, stable, stand mute, stay-at-home,
   still, strangle, subvert, surround, undermine, upset, wall in,
   wrap, yard, yard up, zip up, zipper

Ball Up >> B Words
Ball Up, definition of term: Ball Up
ball+up_pag1.html

Bang Up >> B Words
Bang Up, definition of term: Bang Up
bang+up_pag1.html

Backed Up >> B Words
Backed Up, definition of term: Backed Up
backed+up_pag1.html

Back Up >> B Words
Back Up, definition of term: Back Up
back+up_pag1.html

Ante Up >> A Words
Ante Up, definition of term: Ante Up
ante+up_pag1.html

Act Up >> A Words
Act Up, definition of term: Act Up
act+up_pag1.html