ultimatum

A final demand or set of conditions, the rejection of which will result in a breakdown of relations, retaliation, or other serious consequences.

• ultimate/ˈʌltɪmət/(adj)最终的

• issue an ultimatum
• deliver an ultimatum
• reject an ultimatum
• face an ultimatum
• ultimatum expires

1. 1.Austria-Hungary's ultimatum to Serbia after the assassination of Archduke Franz Ferdinand — with deliberately unacceptable terms — was designed to provoke war and triggered WWI. (diplomatic final demand)
2. 2.She gave her boss an ultimatum: either address the toxic workplace culture within thirty days or she would resign publicly. (non-negotiable demand)

• final demand (last non-negotiable request)
• deadline demand (time-pressured requirement)

from Latin "ultimatum" (a final thing) — from "ultimus" (last) — the last word before consequences