M-day

[ em-dey ]

noun

, Military.

1. mobilization day: a day assumed by the Department of Defense as the first day of mobilization, used by the military for planning purposes.

Word History and Origins

Origin of M-day¹

First recorded in 1935–40

Example Sentences

John M. Day, Morris Township, was a good-hearted man, but seemed physically unable to withstand the hardships of active service.

From Project Gutenberg