pledge

To make a solemn promise (to do something).

pledge allegiance to the flag

To deposit something as a security; to pawn.

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.

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.

A solemn promise to do something.

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.

A bailment of personal property to secure payment of a debt without transfer of title.

A bailment of personal property to secure payment of a debt without transfer of title.