a solemn and binding promise or undertaking

an undertaking, esp to donate money to charity

something given as a token of love, remembrance, loyalty, etc

something handed over to an authority as security, redeemable only on the fulfilment of a promise, discharge of a debt, etc

(the pledge) an undertaking to abstain from drinking alcohol

archaic a toast or drink to a person's health

to promise (something or to do something)

They pledged their allegiance to the flag

to deposit (something) as security

to bind (somebody) by or as if by a solemn promise

archaic to drink the health of (somebody)