Search Result for "ultimatum": 
Wordnet 3.0

NOUN (1)

1. a final peremptory demand;

The Collaborative International Dictionary of English v.0.48:

Ultimatum \Ul`ti*ma"tum\ ([u^]l`t[i^]*m[=a]"t[u^]m), n.; pl. E. Ultimatums ([u^]l`t[i^]*m[=a]"t[u^]mz), 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]
WordNet (r) 3.0 (2006):

ultimatum n 1: a final peremptory demand
Moby Thesaurus II by Grady Ward, 1.0:

84 Moby Thesaurus words for "ultimatum": admonishment, admonition, alarm, blackmail, boundary condition, call, call for, catch, caution, caveat, claim, clause, condition, conditions, contribution, demand, demand for, demands, deterrent example, donnee, draft, drain, duty, escalator clause, escape clause, escape hatch, exaction, example, extortion, extortionate demand, final notice, final offer, final warning, fine print, firm price, given, grounds, heavy demand, hint, imposition, impost, indent, insistent demand, joker, kicker, last word, lesson, levy, limiting condition, monition, moral, nonnegotiable demand, notice, notification, object lesson, obligation, order, parameter, prerequisite, provision, provisions, proviso, requirement, requisite, requisition, rush, rush order, saving clause, sine qua non, small print, specification, stipulation, stipulations, string, tax, taxing, terms, threat, tip-off, tribute, verbum sapienti, warning, warning piece, whereas
Bouvier's Law Dictionary, Revised 6th Ed (1856):

ULTIMATUM. The last proposition made in making a contract, a treaty, and the like; as, the government of the United States has given its ultimatum, has made the last proposition it will make to complete the proposed treaty. The word also means the result of a negotiation, and it comprises the final determination of the parties concerned in the object in dispute.
The Devil's Dictionary (1881-1906):

ULTIMATUM, n. In diplomacy, a last demand before resorting to concessions. Having received an ultimatum from Austria, the Turkish Ministry met to consider it. "O servant of the Prophet," said the Sheik of the Imperial Chibouk to the Mamoosh of the Invincible Army, "how many unconquerable soldiers have we in arms?" "Upholder of the Faith," that dignitary replied after examining his memoranda, "they are in numbers as the leaves of the forest!" "And how many impenetrable battleships strike terror to the hearts of all Christian swine?" he asked the Imaum of the Ever Victorious Navy. "Uncle of the Full Moon," was the reply, "deign to know that they are as the waves of the ocean, the sands of the desert and the stars of Heaven!" For eight hours the broad brow of the Sheik of the Imperial Chibouk was corrugated with evidences of deep thought: he was calculating the chances of war. Then, "Sons of angels," he said, "the die is cast! I shall suggest to the Ulema of the Imperial Ear that he advise inaction. In the name of Allah, the council is adjourned."