Dictionary:

cancellation

  (kăn'sə-lā'shən)

1. The act or an instance of canceling.
2. A mark or a perforation indicating canceling.
3. Something canceled, especially a released accommodation or an unfilled appointment.

noun

1. The act of erasing or the condition of being erased: deletion, erasure, expunction, obliteration. See include/exclude.
2. An often formal act of putting an end to: abolishment, abolition, abrogation, annihilation, annulment, defeasance, invalidation, negation, nullification, voidance. Law avoidance, extinguishment. See continue/stop/pause.

Definition: calling off; erasure
Antonyms: allowance, approval, arrangement, confirmation, establishment, permission, ratification