ultimatum

n.; pl. E. Ultimatums L. Ultimata [ NL. See Ultimate. ] 1. A final proposition, concession, or condition; especially, the final propositions, conditions, or terms, offered by either of the parties in a diplomatic negotiation; the most favorable terms that a negotiator can offer, the rejection of which usually puts an end to the hesitation. [ 1913 Webster ]

2. A final demand, the rejection of which may lead to a resort to force or other compelling action by the party presenting the ultimatum. In international diplomacy, an ultimatum may be used as by the demanding country as a signal to other countries that it gave the other country a seemingly reasonable opportunity to avoid a war; in this way, the demanding country may seek to avoid responsibility for starting a war. [ PJC ]

[ 1913 Webster ]