S: (n) assurance, pledge (a binding commitment to do or give or refrain from something) "an assurance of help when needed"; "signed a pledge never to reveal the secret"
Verb
S: (v) pledge, plight (promise solemnly and formally) "I pledge that I will honor my wife"
S: (v) pledge, subscribe (pay (an amount of money) as a contribution to a charity or service, especially at regular intervals) "I pledged $10 a month to my favorite radio station"