The Collaborative International Dictionary of English v.0.48:
Pledge \Pledge\, v. t. [imp. & p. p. Pledged; p. pr. & vb. n.
Pledging.] [Cf. OF. pleiger to give security. See Pledge,
1. To deposit, as a chattel, in pledge or pawn; to leave in
possession of another as security; as, to pledge one's
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
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