ultimatum
n. countablen. a final demand that someone must accept to avoid a serious problem or punishment. It is a 'do this or else' message.
n. a final demand or statement of terms, the rejection of which will result in retaliation or a breakdown in relations. Often used in diplomatic, legal, or interpersonal negotiations.
She gave him an ultimatum: arrive on time or leave.
The union issued an ultimatum to the management, threatening a full-scale strike if the safety demands were not met by midnight.
History is replete with diplomatic ultimatums that, while intended to force a peaceful concession, ultimately served as the formal precursors to declarations of war.
From Latin ultimatus (“late, last final”), from Latin ultimus (“extreme, last, furthest, farthest, final”).
Commonly follows the verbs 'issue', 'give', or 'deliver'.