pledge
n. countablen. a serious promise to do something or to give money. You use this when you want to show you are very committed to a goal.
n. a solemn promise or undertaking, often involving a financial commitment or a formal oath of loyalty.
The politician made a pledge to lower taxes.
The university received a million-dollar pledge from a former student to build a new library.
Despite the public pledge to reduce carbon emissions by half, the corporation continued to invest heavily in fossil fuel extraction projects across the globe.
From Middle English plege, from Anglo-Norman plege, from Old French plege (Modern French pleige) from Medieval Latin plevium, plebium, from plebiō (“to 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.
Often followed by the preposition 'of' or an infinitive 'to' phrase.