The Collaborative International Dictionary of English v.0.48:

Rescue \Res"cue\ (r[e^]s"k[-u]), n. [From Rescue, v.; cf.
   Rescous.]
   [1913 Webster]
   1. The act of rescuing; deliverance from restraint, violence,
      or danger; liberation.
      [1913 Webster]

            Spur to the rescue of the noble Talbot. --Shak.
      [1913 Webster]

   2. (Law)
      (a) The forcible retaking, or taking away, against law, of
          things lawfully distrained.
      (b) The forcible liberation of a person from an arrest or
          imprisonment.
      (c) The retaking by a party captured of a prize made by
          the enemy. --Bouvier.
          [1913 Webster]

                The rescue of a prisoner from the court is
                punished with perpetual imprisonment and
                forfeiture of goods.              --Blackstone.
          [1913 Webster]

   Rescue grass. [Etymol. uncertain.] (Bot.) A tall grass
      (Ceratochloa unioloides) somewhat resembling chess,
      cultivated for hay and forage in the Southern States.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Rescue \Res"cue\ (r[e^]s"k[-u]), v. t. [imp. & p. p. Rescued
   (-k?d);p. pr. & vb. n. Rescuing.] [OE. rescopuen, OF.
   rescourre, rescurre, rescorre; L. pref. re- re- + excutere to
   shake or drive out; ex out + quatere to shake. See Qtash to
   crush, Rercussion.]
   To free or deliver from any confinement, violence, danger, or
   evil; to liberate from actual restraint; to remove or
   withdraw from a state of exposure to evil; as, to rescue a
   prisoner from the enemy; to rescue seamen from destruction.
   [1913 Webster]

         Had I been seized by a hungry lion,
         I would have been a breakfast to the best,
         Rather than have false Proteus rescue me. --Shak.
   [1913 Webster]

   Syn: To retake; recapture; free; deliver; liberate; release;
        save.
        [1913 Webster]

WordNet (r) 3.0 (2006):

rescue
    n 1: recovery or preservation from loss or danger; "work is the
         deliverance of mankind"; "a surgeon's job is the saving of
         lives" [syn: rescue, deliverance, delivery, saving]
    v 1: free from harm or evil [syn: rescue, deliver]
    2: take forcibly from legal custody; "rescue prisoners"

Moby Thesaurus II by Grady Ward, 1.0:

107 Moby Thesaurus words for "rescue":
   Emancipation Proclamation, abet, affranchise, affranchisement, aid,
   assist, assistance, avail, bail out, bear a hand, befriend,
   benefit, break, breakout, buy, comfort, conserve, deliver,
   deliverance, delivery, disembarrass, disentangle, disenthrall,
   disenthrallment, do good, doctor, ease, emancipate, emancipation,
   emergence, enfranchise, enfranchisement, escape, escapism, evasion,
   extract, extricate, extrication, favor, flight, free, freeing,
   gay liberation, getaway, give a boost, give a hand, give a lift,
   give help, good offices, help, issuance, issue, jailbreak, leak,
   leakage, lend a hand, lend one aid, let go free, let loose,
   liberate, liberation, manumission, manumit, ministration, ministry,
   office, offices, outlet, preserve, prisonbreak, proffer aid,
   protect, protection, rally, ransom, reclaim, recoup, recover,
   recycle, redeem, regain, release, relief, relieve, remedy,
   render assistance, restore, resuscitate, retrieve, revive,
   riddance, salvage, save, saving, service, set at large,
   set at liberty, set free, set up, setting at liberty, setting-free,
   succor, support, take in tow, therapy, vent, win back



Bouvier's Law Dictionary, Revised 6th Ed (1856):

RESCUE, crim. law. A forcible setting at liberty against law of a person
duly arrested. Co. Litt. 160; 1 Chitty's Cr, Law, *62; 1 Russ. on Cr. 383.
The person who rescues the prisoner is called the rescuer.
     2. If the rescued prisoner were arrested for felony, then the rescuer
is a felon; if for treason, a traitor; and if for a trespass, he is liable
to a fine as if he had committed the original offence. Hawk. B. 5, c. 21. If
the principal be acquitted, the rescuer may nevertheless be fined for the
misdemeanor in the obstruction and contempt of public justice. 1 Hale, 598.
     3. In order to render the rescuer criminal, it is necessary he should
have knowledge that the person whom he sets at liberty has been apprehended
for a criminal offence, if he is in the custody of a private person; but if
he be under the care of a public officer, then he is to take notice of it at
his peril. 1 Hale, 606.
     4. In another sense, rescue is the taking away and setting at liberty,
against law, a distress taken for rent, or services, or damage feasant. Bac.
Ab. Rescue, A.
     5. For the law of the United States on this subject, vide Ing. Dig.
150. Vide, generally, 19 Vin. Ab. 94.



Bouvier's Law Dictionary, Revised 6th Ed (1856):

RESCUE, mar. war. The retaking by a party captured of a prize made by the
enemy. There is still another kind of rescue which partake's of the nature
of a recapture; it occurs when the weaker party before he is overpowered,
obtains relief from the arrival of fresh succors, and is thus preserved from
the force of the enemy. 1 Rob. Rep. 224; 1 Rob. Rep. 271.
     2. Rescue differs from recapture. (q.v.) The rescuers do not by the
rescue become owners of the property, as if it had been a new prize -- but
the property is restored to the original owners by the right of
postliminium. (q.v.)