doomsday

 
Pronunciation: /ˈduːmzdeɪ/

noun

  • the last day of the world’s existence: Bede believed that the time of doomsday is concealed from mankind
  • (in religious belief) the day of the Last Judgement.
  • a time or event of crisis or great danger: [as modifier]: in all the concern over greenhouse warming, one doomsday scenario stands out

Phrases

till doomsday

informal forever: we’ll be here till doomsday if you go blethering on

Origin:

Old English dōmes dæg (see doom, day)