Pledge
A solemn or formal promise, especially one to give money or to be a friend, or something that you give as a sign that you will keep a promise:[ + to infinitive ] All the candidates have given/made pledges not to raise taxes if they are elected. Thousands of people made pledges (= promised to give money) to the charity campaign. I give you this ring as a pledge of my everlasting love for you [Cambridge Dictionary].
An article was given by a borrower (pledgor) to a lender ( pledgee) as a security for a debt. It remains in the ownership of the pledgor, although it has the pledgee until [A Dictionary of Economics].
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. Something given or held as security to guarantee payment of a debt or fulfillment of an obligation. The condition of something thus given or held: put an article in the pledge [The free dictionary].
A bailment of a chattel as security for a debt or other obligation without involving the transfer of title: the chattel so delivered, the contract incidental to such a bailment, the state of being held as security or guaranty, something given as security for the performance of an act, a token, sign, or earnest of something else, a gage of battle [Merriam-Webster].
Pledge. Cambridge Dictionary. Retrieved from: https://dictionary.cambridge.org/dictionary/english/pledge
Black John, Hashimzade Nigar, and Myles Gareth. (2009). A Dictionary of Economics. Pledge. Retrieved from: https://www.oxfordreference.com/search?q=pledge&searchBtn=Search&isQuickSearch=true
What is the pledge? The free dictionary. Retrieved from: https://www.thefreedictionary.com/pledge
Pledge. Merriam-Webster Dictionary (курсив). Retrieved from: https://www.merriam-webster.com/dictionary/pledge