Revocable / Irrevocable

Revocable means something that can be rescinded or withdrawn. For example, a revocable contract offer is an offer that the offeror can cancel before the offeree accepts the offer without any legal consequence. A revocable agreement is an agreement that can be canceled by one party without any consequence.

Irrevocable is the opposite of revocable. An irrevocable offer must stay open for a certain period of time. That is, the offeror cannot withdraw the offer during a specific time period while the offeree decides whether to accept the offer or not.