If you cancel something that has been arranged, you stop it from happening. If you cancel an order for goods or services, you tell the person or organization supplying them that you no longer wish to receive them.

If someone in authority cancels a document, an insurance policy, or a debt, they officially declare that it is no longer valid or no longer legally exists.

To cancel a stamp or a cheque means to mark it to show that it has already been used and cannot be used again.