pledge

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.]”

   “Reach me my golden cup that stands by thee, And pledge me in it first for courtesy.”

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.”

2. A solemn promise to do something.
3. 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.

   “Iacke Straw. […] I haue his wife and children pledges, for his ſpeedie returne from the King, to whom he is gone with our meſſage. Tom Miller. Let him take heede hee bring a wiſe anſwere to our worships, or els his pledges goes to the pot.”

4. A bailment of personal property to secure payment of a debt without transfer of title.
5. A bailment of personal property to secure payment of a debt without transfer of title.
6. A person who has taken a pledge of allegiance to a college fraternity, but is not yet formally approved.
7. A drinking toast.