What is the meaning of pledge?

noun

• A deposit of personal property as security for a debt.
  • usage: "his saxophone was in pledge"
• Someone accepted for membership but not yet fully admitted to the group.
• A drink in honor of or to the health of a person or event.
  • synonyms: toast
• A binding commitment to do or give or refrain from something.
  • usage: "an assurance of help when needed"; "signed a pledge never to reveal the secret"
  • synonyms: assurance

verb

• Promise solemnly and formally.
  • usage: "I pledge that I will honor my wife"
  • synonyms: plight
• Pay (an amount of money) as a contribution to a charity or service, especially at regular intervals.
  • usage: "I pledged $10 a month to my favorite radio station"
  • synonyms: subscribe
• Propose a toast to.
  • usage: "Let us toast the birthday girl"; "Let's drink to the New Year"
  • synonyms: toast, drink, salute, wassail
• Give as a guarantee.
  • usage: "I pledge my honor"
• Bind or secure by a pledge.
  • usage: "I was pledged to silence"