WordNet (r) 3.0 (2006):

shut down
    v 1: cease to operate or cause to cease operating; "The owners
         decided to move and to close the factory"; "My business
         closes every night at 8 P.M."; "close up the shop" [syn:
         close up, close, fold, shut down, close down]
         [ant: open, open up]

Moby Thesaurus II by Grady Ward, 1.0:

90 Moby Thesaurus words for "shut down":
   asphyxiate, be ruined, become insolvent, bottle up, break, bust,
   call a strike, call it quits, cease, censor, choke, choke off,
   clamp down on, close, close down, close shop, close up, collapse,
   cork, cork up, crack down on, crash, crush, cut, damp down, drown,
   dumbfound, extinguish, fail, fold, fold up, gag, go bankrupt,
   go broke, go into receivership, go on strike, go to pot,
   go to ruin, go under, go up, hold down, hush, hush-hush, jump on,
   keep down, keep under, kill, knock off, lay off, muffle, muzzle,
   pour water on, put down, put to silence, quash, quell, quench,
   quiet, quieten, repress, secure, shush, shut, shut down on,
   shut off, shut up, shut up shop, shutter, silence, sit down on,
   sit on, smash, smother, soft-pedal, squash, squelch, stanch,
   stifle, still, strangle, strike, strike dumb, stultify, subdue,
   suffocate, suppress, switch off, throttle, turn off, walk out