The Collaborative International Dictionary of English v.0.48:

Sequester \Se*ques"ter\, v. t. [imp. & p. p. Sequestered; p.
   pr. & vb. n. Sequestering.] [F. s['e]questrer, L.
   sequestrare to give up for safe keeping, from sequester a
   depositary or trustee in whose hands the thing contested was
   placed until the dispute was settled. Cf. Sequestrate.]
   1. (Law) To separate from the owner for a time; to take from
      parties in controversy and put into the possession of an
      indifferent person; to seize or take possession of, as
      property belonging to another, and hold it till the
      profits have paid the demand for which it is taken, or
      till the owner has performed the decree of court, or
      clears himself of contempt; in international law, to
      confiscate.
      [1913 Webster]

            Formerly the goods of a defendant in chancery were,
            in the last resort, sequestered and detained to
            enforce the decrees of the court. And now the
            profits of a benefice are sequestered to pay the
            debts of ecclesiastics.               --Blackstone.
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   2. To cause (one) to submit to the process of sequestration;
      to deprive (one) of one's estate, property, etc.
      [1913 Webster]

            It was his tailor and his cook, his fine fashions
            and his French ragouts, which sequestered him.
                                                  --South.
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   3. To set apart; to put aside; to remove; to separate from
      other things.
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            I had wholly sequestered my civil affairss. --Bacon.
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   4. To cause to retire or withdraw into obscurity; to seclude;
      to withdraw; -- often used reflexively.
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            When men most sequester themselves from action.
                                                  --Hooker.
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            A love and desire to sequester a man's self for a
            higher conversation.                  --Bacon.
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The Collaborative International Dictionary of English v.0.48:

Sequester \Se*ques"ter\, v. i.
   1. To withdraw; to retire. [Obs.]
      [1913 Webster]

            To sequester out of the world into Atlantic and
            Utopian politics.                     --Milton.
      [1913 Webster]

   2. (Law) To renounce (as a widow may) any concern with the
      estate of her husband.
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The Collaborative International Dictionary of English v.0.48:

Sequester \Se*ques"ter\, n.
   1. Sequestration; separation. [R.]
      [1913 Webster]

   2. (Law) A person with whom two or more contending parties
      deposit the subject matter of the controversy; one who
      mediates between two parties; a mediator; an umpire or
      referee. --Bouvier.
      [1913 Webster]

   3. (Med.) Same as Sequestrum.
      [1913 Webster]

WordNet (r) 3.0 (2006):

sequester
    v 1: requisition forcibly, as of enemy property; "the estate was
         sequestered"
    2: take temporary possession of as a security, by legal
       authority; "The FBI seized the drugs"; "The customs agents
       impounded the illegal shipment"; "The police confiscated the
       stolen artwork" [syn: impound, attach, sequester,
       confiscate, seize]
    3: undergo sequestration by forming a stable compound with an
       ion; "The cations were sequestered"
    4: keep away from others; "He sequestered himself in his study
       to write a book" [syn: seclude, sequester, sequestrate,
       withdraw]
    5: set apart from others; "The dentist sequesters the tooth he
       is working on" [syn: sequester, sequestrate, keep
       apart, set apart, isolate]

Moby Thesaurus II by Grady Ward, 1.0:

75 Moby Thesaurus words for "sequester":
   abrupt, accroach, alienate, annex, arrogate, attach, cast off,
   cast out, cloister, close off, collectivize, commandeer,
   communalize, communize, confiscate, cut adrift, cut off, cut out,
   delete, depart, disarticulate, disconnect, disengage, disjoin,
   disjoint, dispossess, dissociate, distrain, disunite, divide,
   divorce, eject, enisle, estrange, expel, expropriate, garnish,
   hide, impound, impress, insulate, island, isolate, leave, levy,
   nationalize, part, preempt, press, pull away, pull back, pull out,
   replevin, replevy, secrete, segregate, seize, separate,
   sequestrate, set apart, set aside, shut off, socialize, split,
   stand aloof, stand apart, stand aside, step aside, subtract, take,
   throw off, throw out, uncouple, unyoke, withdraw