<p><strong>Noun</strong></p><ul><li>The day of the Last Judgment, at the end of the world</li><li>any day of judgment or sentence</li><li>nuclear destruction of the world</li></ul><p><strong>Adjective</strong></p><ul><li>given to or marked by forebodings or predictions of impending calamity; especially concerned with or predicting future universal destruction: the doomsday issue of all-out nuclear war</li><li>capable of causing widespread or total destruction: doomsday weapons</li></ul>