The Collaborative International Dictionary of English v.0.48:

Ransack \Ran"sack\ (r[a^]n"s[a^]k), v. t. [imp. & p. p.
   Ransacked (-s[a^]kt); p. pr. & vb. n. Ransacking.] [OE.
   ransaken, Icel. rannsaka to explore, examine; rann a house
   (akin to Goth. razn house, AS. r[ae]sn plank, beam) + the
   root of s[ae]kja to seek, akin to E. seek. See Seek, and
   cf. Rest repose.]
   1. To search thoroughly; to search every place or part of;
      as, to ransack a house.
      [1913 Webster]

            To ransack every corner of their . . . hearts.
                                                  --South.
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   2. To plunder; to pillage completely.
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            Their vow is made
            To ransack Troy.                      --Shak.
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   3. To violate; to ravish; to defiour. [Obs.]
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            Rich spoil of ransacked chastity.     --Spenser.
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The Collaborative International Dictionary of English v.0.48:

Ransack \Ran"sack\, v. i.
   To make a thorough search.
   [1913 Webster]

         To ransack in the tas [heap] of bodies dead. --Chaucer.
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The Collaborative International Dictionary of English v.0.48:

Ransack \Ran"sack\, n.
   The act of ransacking, or state of being ransacked; pillage.
   [R.]
   [1913 Webster]

         Even your father's house
         Shall not be free from ransack.          --J. Webster.
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WordNet (r) 3.0 (2006):

ransack
    v 1: steal goods; take as spoils; "During the earthquake people
         looted the stores that were deserted by their owners" [syn:
         plunder, despoil, loot, reave, strip, rifle,
         ransack, pillage, foray]
    2: search thoroughly; "They combed the area for the missing
       child" [syn: comb, ransack]

Moby Thesaurus II by Grady Ward, 1.0:

48 Moby Thesaurus words for "ransack":
   beat, burglarize, burgle, comb, depredate, despoil, examine,
   explore, fleece, forage, foray, freeboot, grub, gut, knock off,
   knock over, look all over, look everywhere, loot, maraud, pillage,
   plunder, prey on, raid, rake, ravage, raven, ravish, reive,
   relieve, rifle, rob, rummage, sack, scour, scrutinize, search,
   search high heaven, shake, shake down, spoil, spoliate, stick up,
   strip, sweep, toss, turn inside out, turn upside down