What is the meaning of Doomsday?

The day when God is expected to judge the world; the end times.

Judgement day; the day of the Final Judgment; any day of decisive judgement or final dissolution.

Any day of great death and destruction; end of the world; an apocalypse.

Any of the memorable dates used in the doomsday rule for computing weekdays from dates.

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.

Source: wiktionary.org