Meaning of X-Day | Babel Free

Definitions

1. 1 November 1945, the planned date for the Allied invasion of Kyushu in southwestern Japan in World War II (cancelled following Japan's unconditional surrender in September 1945).
   historical
2. Synonym of D-Day (“the date of any major event planned for the future”).
3. An annual celebration in the Church of the SubGenius parody religion, falling on July 5 and commemorating the prophesied end of the world on that date in 1998, when alien beings from "Planet X" were to have invaded.

CEFR level