The Collaborative International Dictionary of English v.0.48:

Seize \Seize\, v. t. [imp. & p. p. Seized; p. pr. & vb. n.
   Seizing.] [OE. seisen, saisen, OF. seisir, saisir, F.
   saisir, of Teutonic origin, and akin to E. set. The meaning
   is properly, to set, put, place, hence, to put in possession
   of. See Set, v. t.]
   1. To fall or rush upon suddenly and lay hold of; to gripe or
      grasp suddenly; to reach and grasp.
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            For by no means the high bank he could seize.
                                                  --Spenser.
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            Seek you to seize and gripe into your hands
            The royalties and rights of banished Hereford?
                                                  --Shak.
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   2. To take possession of by force.
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            At last they seize
            The scepter, and regard not David's sons. --Milton.
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   3. To invade suddenly; to take sudden hold of; to come upon
      suddenly; as, a fever seizes a patient.
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            Hope and deubt alternate seize her seul. --Pope.
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   4. (law) To take possession of by virtue of a warrant or
      other legal authority; as, the sheriff seized the debtor's
      goods.
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   5. To fasten; to fix. [Obs.]
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            As when a bear hath seized her cruel claws
            Upon the carcass of some beast too weak. --Spenser.
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   6. To grap with the mind; to comprehend fully and distinctly;
      as, to seize an idea.
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   7. (Naut.) To bind or fasten together with a lashing of small
      stuff, as yarn or marline; as, to seize ropes.
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   Note: This word, by writers on law, is commonly written
         seise, in the phrase to be seised of (an estate), as
         also, in composition, disseise, disseisin.
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   To be seized of, to have possession, or right of
      possession; as, A B was seized and possessed of the manor
      of Dale. "Whom age might see seized of what youth made
      prize." --Chapman.

   To seize on or To seize upon, to fall on and grasp; to
      take hold on; to take possession of suddenly and forcibly.
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   Syn: To catch; grasp; clutch; snatch; apprehend; arrest;
        take; capture.
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WordNet (r) 3.0 (2006):

seize
    v 1: take hold of; grab; "The sales clerk quickly seized the
         money on the counter"; "She clutched her purse"; "The
         mother seized her child by the arm"; "Birds of prey often
         seize small mammals" [syn: seize, prehend, clutch]
    2: take or capture by force; "The terrorists seized the
       politicians"; "The rebels threaten to seize civilian
       hostages"
    3: take possession of by force, as after an invasion; "the
       invaders seized the land and property of the inhabitants";
       "The army seized the town"; "The militia captured the castle"
       [syn: appropriate, capture, seize, conquer]
    4: 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]
    5: seize and take control without authority and possibly with
       force; take as one's right or possession; "He assumed to
       himself the right to fill all positions in the town"; "he
       usurped my rights"; "She seized control of the throne after
       her husband died" [syn: assume, usurp, seize, take
       over, arrogate]
    6: hook by a pull on the line; "strike a fish"
    7: affect; "Fear seized the prisoners"; "The patient was seized
       with unbearable pains"; "He was seized with a dreadful
       disease" [syn: seize, clutch, get hold of]
    8: capture the attention or imagination of; "This story will
       grab you"; "The movie seized my imagination" [syn: grab,
       seize]

Moby Thesaurus II by Grady Ward, 1.0:

138 Moby Thesaurus words for "seize":
   abduct, absorb, accroach, adopt, afflict, annex, appreciate,
   apprehend, appropriate, arrest, arrogate, assimilate, assume,
   assume command, be acquainted with, be apprised of, be aware of,
   be cognizant of, be conscious of, be conversant with, be informed,
   be with one, beset, bind, bust, capture, carry, carry off, catch,
   catch at, catch on, clutch, cognize, collar, commandeer,
   comprehend, conceive, conceptualize, confiscate, dig, digest,
   discern, encroach, expropriate, fasten, fasten upon, fathom,
   follow, get, get hold of, get the drift, get the idea,
   get the picture, grab, grapple, grasp, grip, have,
   have information about, have it taped, have knowledge of, hold,
   impound, infringe, invade, jam, jump, jump at, ken, kidnap, know,
   latch, learn, lock up, make an arrest, make out, master,
   mount the throne, nab, nail, net, nick, occupy, perceive, pick up,
   pinch, play God, possess, pounce upon, preempt, prehend,
   pretend to, put under arrest, read, realize, recognize, round up,
   savvy, scramble for, secure, see, seize on, seize power,
   seize the meaning, seize the throne, sense, sequester, shanghai,
   snap at, snatch, snatch at, spring upon, stick, stop, subject,
   swoop down upon, take, take advantage of, take away, take captive,
   take charge, take command, take hold of, take in,
   take into custody, take over, take possession of, take prisoner,
   take the helm, take the lead, throttle, transfix, trespass,
   understand, usurp, visit, wot, wot of