The Collaborative International Dictionary of English v.0.48:

Pledge \Pledge\, n. [OF. plege, pleige, pledge, guaranty, LL.
   plegium, plivium; akin to OF. plevir to bail, guaranty,
   perhaps fr. L. praebere to proffer, offer (sc. fidem a trust,
   a promise of security), but cf. also E. play. [root]28. Cf.
   Prebend, Replevin.]
   1. (Law) The transfer of possession of personal property from
      a debtor to a creditor as security for a debt or
      engagement; also, the contract created between the debtor
      and creditor by a thing being so delivered or deposited,
      forming a species of bailment; also, that which is so
      delivered or deposited; something put in pawn.
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   Note: Pledge is ordinarily confined to personal property; the
         title or ownership does not pass by it; possession is
         essential to it. In all these points it differs from a
         mortgage [see Mortgage]; and in the last, from the
         hypotheca of the Roman law. See Hypotheca. --Story.
         Kent.
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   2. (Old Eng. Law) A person who undertook, or became
      responsible, for another; a bail; a surety; a hostage. "I
      am Grumio's pledge." --Shak.
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   3. A hypothecation without transfer of possession.
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   4. Anything given or considered as a security for the
      performance of an act; a guarantee; as, mutual interest is
      the best pledge for the performance of treaties. "That
      voice, their liveliest pledge of hope." --Milton.
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   5. A promise or agreement by which one binds one's self to
      do, or to refrain from doing, something; especially, a
      solemn promise in writing to refrain from using
      intoxicating liquors or the like; as, to sign the pledge;
      the mayor had made no pledges.
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   6. A sentiment to which assent is given by drinking one's
      health; a toast; a health.
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   Dead pledge. [A translation of LL. mortuum vadium.] (Law)
      A mortgage. See Mortgage.

   Living pledge. [A translation of LL. vivum vadium.] (Law)
      The conveyance of an estate to another for money borrowed,
      to be held by him until the debt is paid out of the rents
      and profits.

   To hold in pledge, to keep as security.

   To put in pledge, to pawn; to give as security.
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   Syn: See Earnest.
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