Definition from Wiktionary, the free dictionary
doomsday (not comparable)
- Concerned with or predicting future universal destruction.
- Given to or marked by forebodings or predictions of impending calamity.
- Capable of causing widespread or total destruction; doomsday weapon.
Derived terms 
Terms derived from the adjective "doomsday"
doomsday (plural doomsdays)
- The day when God is expected to judge the world; end times.
- judgement day; the day of the Final Judgment; any day of decisive judgement or final dissolution.
day when God is expected to judge the world
any day of decisive judgement
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