A ultimatum (in Latin, last thing ) is a final requirement formulated by an entity, a group or a person against the opposing party, whose achievement is necessary inside a specific time and who is accompanied by a Menace implicit or explicit in the event of non-fulfilment. An ultimatum is generally a final request which makes following a series of requests. As such, the allowed time is usually short, and the requirement is regarded as not being negotiable.

The threat which accompanies an ultimatum can vary according to the nature of the request and the circumstances. For example:

• in Diplomacy, the threat of a Declaration of war, catch of other military actions, imposition of sanctions such as commercial restrictions or Embargo S.
• at the time of a Kidnapping, the threat by the kidnappers to kill the Hostage S, or by the authorities, to recover the latter by the force.