canceller

A canceller is a person or device that cancels something. In common usage, a canceller prevents or nullifies an arrangement, action, or document. The term is used across domains to denote a mechanism that stops a process, erases a signal, or marks something as invalid.

In philately, a canceller refers to a device or impression used to prevent the reuse of postage stamps. Cancellations are applied to stamps to deface them, typically displaying the date and place of cancellation, and may be produced by hand stamps or by machines.

In telecommunications and signal processing, cancellation refers to removing unwanted components from a signal. An echo canceller or noise canceller is a system that models and subtracts unwanted echoes or noise from the received signal. In software and computing, a canceller can describe a cancellation mechanism, such as a cancellation token or request that signals a running task or operation to terminate.

In legal, administrative, or archival contexts, a canceller may refer to a device or process used to invalidate or cancel a document, contract, or record, though terminology and practices vary by jurisdiction. The term emphasizes the act of rendering something void or nonfunctional, whether applied to physical items, digital processes, or formal agreements.