pledge

Etymology

From Middle English plege, from Anglo-Norman plege, from Old French plege (Modern French pleige) from Medieval Latin plevium, plebium, from plebiō (“I pledge”), from Frankish *plehan (“to pledge; to support; to guarantee”). Akin to Old High German pflegan (“to take care of, be accustomed to”), Old Saxon plegan (“to vouch for”), Old English plēon (“to risk, endanger”). More at plight.

verb

1. To make a solemn promise (to do something).
   pledge allegiance to the flag
2. To deposit something as a security; to pawn.
3. (transitive) To give assurance of friendship by the act of drinking; to drink to one's health.
   HARDCASTLE [Taking the cup.] I hope you'll find it to your mind. I have prepared it with my own hands, and I believe you'll own the ingredients are tolerable. Will you be so good as to pledge me, sir? Here, Mr. Marlow, here is to our better acquaintance. [Drinks.] 1773, Oliver Goldsmith, She Stoops to Conquer
   Reach me my golden cup that stands by thee, And pledge me in it first for courtesy. 1852, Matthew Arnold, Tristram and Iseult

noun

1. A solemn promise to do something.
   Mr. Biden unveiled the pledge at a White House climate summit for world leaders, declaring that the United States is ready to reclaim a leadership role on climate change. April 22, 2021, Brad Plumer, Nadja Popovich, “The U.S. Has a New Climate Goal. How Does It Stack Up Globally?”, in The New York Times, →ISSN
   1. (with the) A promise to abstain from drinking alcohol.
2. An asset or person temporarily handed over to guarantee the fulfilment of something promised, under threat of permanent loss of the thing handed over; surety, security, hostage.
3. (law) A bailment of personal property to secure payment of a debt without transfer of title.
   1. The personal property so pledged, to be kept until the debt is paid.
4. (university slang) A person who has taken a pledge of allegiance to a college fraternity, but is not yet formally approved.
5. A drinking toast.