Emily Dickinson Lexicon

PLEDGE, v.t. [Fr. pleiger. See Plight.]

1. To deposit in pawn; to deposit or leave in possession of a person something which is to secure the repayment of money borrowed, or the performance of some act. [This word is applied chiefly to the depositing of goods or personal property. When real estate is given as security, we usually apply the word mortgage.]
2. To give as a warrant or security; as, to pledge one's word or honor; to pledge one's veracity.
3. To secure by a pledge. I accept her, / And here to pledge my vow I give my hand. [Unusual.] – Shak.
4. To invite to drink by accepting the cup or health after another. Johnson. Or to warrant or be surety for a person that he shall receive no harm while drinking, or from the draught; a practice which originated among our ancestors in their rude state, and which was intended to secure the person from being stabbed while drinking, or from being poisoned by the liquor. In the first case, a by-stander pledges the person drinking; in the latter, the person drinking pledges his guest by drinking first, and then handing the cup to his guest. The latter practice is frequent among the common people in America to this day; the owner of the liquor taking the cup says to his friend, I pledge you, and drinks, then hands the cup to his guest; a remarkable instance of the power of habit, as the reason of the custom has long since ceased.
5. To engage by promise or declaration.