40 mike-mike

In real, traceable use. Part of the curated seed collection; community review is coming.

Meaning · English

Any weapon firing a 40mm grenade. Often specifically the M203 grenade launcher, mounted underneath an M-16 or its variant. In the Marine Corps, often the Mark-19 Automatic 40mm Grenade Launcher.

Register: slang

Where it’s used: Used American English
Sources & notes

Adapted from English Wiktionary (CC BY-SA 4.0, retrieved 2026-07-30 via kaikki.org).

Common questions

What does “40 mike-mike” mean?

Any weapon firing a 40mm grenade. Often specifically the M203 grenade launcher, mounted underneath an M-16 or its variant. In the Marine Corps, often the Mark-19 Automatic 40mm Grenade Launcher.

Is “40 mike-mike” formal or informal?

40 mike-mike is generally slang.