X-Day

proper noun

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).

Similar
D-Day
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Meanings

proper noun
  1. historical1 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).
  2. 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.
nounX-Day (plural X-Days)

plural X-Days · alternative X-day

  1. Synonym of D-Day (“the date of any major event planned for the future”).

    Synonyms: D-Day

Synonyms & antonyms

nounSynonym of D-Day (“the date of any major event planned for the future”).

Similar
D-Day
Also see
d-day
Cite this entry
APA

X-Day. (n.d.). In WatkinsX Dictionary. Retrieved November 3, 2026, from https://dictionary.watkinsx.com/word/X-Day

MLA

“X-Day.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/X-Day. Accessed November 3, 2026.

Chicago

WatkinsX Dictionary, s.v. “X-Day,” accessed November 3, 2026, https://dictionary.watkinsx.com/word/X-Day.

Source: X-Day on Wiktionary, CC BY-SA 4.0.