A penetrating oil used as a lubricant and to protect electric circuits from moisture.

Alternative form of 40s

Alternative letter-case form of top 40

(US Army and Marines, military, slang) Any weapon firing a 40mm grenade. Often specifically the M203 grenade launcher, mounted underneath an M-16 or variant. In the Marine Corps, often the Mark-19 Automatic 40mm Grenade Launcher.

The geographic region between 10 degrees north and 40 degrees north latitude, especially when considered as a target for Christian missionary work.