WordNet (r) 3.0 (2006):

lock up
    v 1: secure by locking; "lock up the house before you go on
         vacation"
    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 up, shut away,
       lock up]

Moby Thesaurus II by Grady Ward, 1.0:

72 Moby Thesaurus words for "lock up":
   bang, bar, barricade, batten, batten down, bolt, bolt in, bosom,
   bottle up, bury, button, button up, cache, cast in prison, choke,
   choke off, clap, clap in jail, clap up, close, close up, constrict,
   contain, contract, cover, deposit, embosom, fasten,
   file and forget, fold, fold up, gaol, hide away, hold captive,
   hold in captivity, hold prisoner, immure, imprison, incarcerate,
   intern, jail, jug, keep hidden, keep secret, key, latch, lock,
   lock in, lock out, occlude, padlock, plant, plumb, put away, seal,
   seal off, seal up, secrete, secure, shut, shut the door, shut up,
   slam, snap, squeeze shut, stash, store away, stow away, strangle,
   throw into jail, zip up, zipper