Doomsday \Dooms"day`\, n. [AS. d?mes d[=a]g. See Doom, and Day.]

1. A day of sentence or condemnation; day of death. ``My body's doomsday.'' --Shak.

2. The day of the final judgment.

I could not tell till doomsday. --Chaucer.

Doomsday Book. See Domesday Book.

Source: Webster's Revised Unabridged Dictionary (1913)