1. [n]  a binding commitment to do or give or refrain from something; "an assurance of help when needed"; "signed a pledge never to reveal the secret"
2. [n]  a drink in honor of or to the health of a person or event
3. [n]  someone accepted for membership but not yet fully admitted to the group
4. [n]  a deposit of personal property as security for a debt; "his saxophone was in pledge"
5. [v]  promise solemnly and formally
6. [v]  bind or secure by a pledge
7. [v]  give as a guarantee; "I pledge my honor"
8. [v]  propose a toast to; "Let us toast the birthday girl!"; "Let's drink to the New Year"
9. [v]  pay (an amount of money) as a contribution to a charity or service, esp. at regular intervals; "I pledged $10 a month to my favorite radio station"

1. \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.
   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.
   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.
   3. A hypothecation without transfer of possession.
   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.
   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.
   6. A sentiment to which assent is given by drinking one's
      health; a toast; a health.
   {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.
   Syn: See {Earnest}.
   

2. \Pledge\, v. t. [imp. & p. p. {Pledged}; p. pr. & vb. n.
   {Pledging}.] [Cf. OF. pleiger to give security. See {Pledge},
   n.]
   1. To deposit, as a chattel, in pledge or pawn; to leave in
      possession of another as security; as, to pledge one's
      watch.
   2. To give or pass as a security; to guarantee; to engage; to
      plight; as, to pledge one's word and honor.
            We mutually pledge to each other our lives, our
            fortunes, and our sacred honor.       --The
                                                  Declaration of
                                                  Independence.
   3. To secure performance of, as by a pledge. [Obs.]
            To pledge my vow, I give my hand.     --Shak.
   4. To bind or engage by promise or declaration; to engage
      solemnly; as, to pledge one's self.
   5. To invite another to drink, by drinking of the cup first,
      and then handing it to him, as a pledge of good will;
      hence, to drink the health of; to toast.
            Pledge me, my friend, and drink till thou be'st
            wise.                                 --Cowley.
   

See LOAN.