An ultimatum (Latin ultimus, the last ',' the ultimate ',' the farthest ') is a requirement which is connected to a (usually short ) time limit for meeting the demand and with the threat of serious consequences in case of non- fulfillment.

An ultimatum is principally a means of politics and was formerly often a declaration of war ahead. Sometimes an ultimatum but also in other areas of life - for example, in the private and professional life - are used. Ethically putting an ultimatum is now mostly considered negative when it comes to relationships or even to blackmail, but it sometimes can prevent a greater disaster in the political sphere.