Definition of M-day

M-Day may refer to:

• M-Day (book) - is a book by Viktor Suvorov about supposed Soviet Army preparations for the invasion of Germany.
• Mobilization Day (M-Day) was to be the day Canadian police would arrest suspected communists under the secret PROFUNC program.
• M-Day is the day on which mobilization commences or is due to commence in NATO per Military designation of days and hours
• Decimation (comics) - A event in the fictional Marvel Universe

M day, M Day, and M-day redirect here; for the Marvel Universe event, see Decimation (comics). H-Hour redirects here; for the D-Day designation, see H-hour (D-day).

The military designation of days and hours within the North Atlantic Treaty Organisation (NATO), is specified in AAP-6 (STANAG 3680), NATO Glossary of Terms and Definitions, and marked (NATO) in what follows. Those entries marked (US) are specific to the U.S., and defined only in Joint Publication JP 1-02, Department of Defense Dictionary of Military and Associated Terms]