1. A final proposition or condition offered, as the basis of a treaty, the rejection of which will put an end to further negotiation; any final proposition or condition.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• ultimat,
• ultamitum,
• ultamatum,
• ultimatam,
• altimatium,
• ultimatium,
• ulimatum,
• ultimatey,
• ultimadem,
• ultimatiums,
• ultimatly,
• ulitmatum,
• ultimatim,
• ultimadum,
• ultimum,
• altamatum,
• ultimatem,
• altimatum,
• ultimateum,
• ultimatie

• ultimacy,
• Ultima Thule,
• ultimateness,
• ultimate,
• ultimately,
• ultimo.

The adjective form of the word "ultimatum" is "ultimate".