pledge
pledge [plĕj] noun
1. A solemn binding promise to do, give, or refrain from doing something: signed a pledge never to reveal the secret; a pledge of money to a charity.
2. a. Something given or held as security to guarantee payment of a debt or fulfillment of an obligation. b. The condition of something thus given or held: put an article in pledge.
3. Law. a. Delivery of goods or personal property as security for a debt or an obligation: a loan that required a pledge of property. b. The contract by which such delivery is made.
4. A token or sign: "fair pledges of a fruitful tree" [Robert Herrick].
5. A person who has been accepted for membership in a fraternity or similar organization and has promised to join but has not yet been initiated.
6. The act of drinking in honor of someone; a toast.
7. A vow to abstain from alcoholic liquor: ex-drinkers who have taken the pledge.
verb
pledged, pledging, pledges
verb, transitive
1. To offer or guarantee by a solemn binding promise: pledge loyalty to a nation; pledged their cooperation. See synonyms at devote.
2. See synonyms at promise.
3. To bind or secure by or as if by a pledge: pledged themselves to the cause.
4. To deposit as security; pawn.
5. a. To promise to join [a fraternity or similar organization]. b. To accept as a prospective member of such an organization.
6. To drink a toast to.
verb, intransitive
1. To make a solemn binding promise; swear.
2. To drink a toast.
[Middle English, from Old French plege, probably from Late Latin plevium, a security, of Germanic origin.]