“40”

The term and slang “40” was popularized in Chicago, Illinois as a word referring to handguns and the gun’s caliber.

A 40 is any weapon (handgun) with a .40 caliber.

The term “40” has been used by Joe Trufant, RondoNumbaNine, Montana of 300 and many more rappers.

Purchase a Rap Dictionary Book

Read: What does “Drip” mean in rap?

Read: What does “Cap” “No Cap” and “Capping” mean?