: a day on which a military mobilization is to begin

Word History

Etymology

mobilization day

First Known Use

1924, in the meaning defined above

Time Traveler
The first known use of M-day was in 1924

Dictionary Entries Near M-day

Cite this Entry

“M-day.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/M-day. Accessed 1 Dec. 2022.

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