doomsday

noun

1. the day of the Last Judgment, at the end of the world.
2. any day of judgment or sentence.
3. nuclear destruction of the world.

adjective

4. 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.
5. capable of causing widespread or total destruction: doomsday weapons.

noun

1. (sometimes capital) the day on which the Last Judgment will occur
2. any day of reckoning
3. (modifier) characterized by predictions of disasterdoomsday scenario

n.

Old English domes dæg, from domes, genitive of dom (see doom (n.)) + dæg “day” (see day (n.)).

In medieval England it was expected when the world’s age reached 6,000 years from creation, which was thought to have been in 5200 B.C. Bede, c.720, complained of being pestered by rustici asking him how many years till the sixth millennium ended. There is no evidence for a general panic in the year 1000 C.E. Doomsday machine “bomb powerful enough to wipe out human life on earth” is from 1960.