Green’s Dictionary of Slang

1. (US black) a nine millimetre pistol.

1997		The Roots ‘The Roots is Comin’’ 🎵 The Roots, is out to blow up like a clip from out the milli or the oo-wop.
2000		Ebonics Primer at www.dolemite.com 🌐 milli Definition: 9mm. Example: You betta back tha fuck up ’for I pull out my milli.

2. (US black) one million (dollars).

2015

Chief Keef ‘Unstoppable’ 🎵 I ran through 2 milli but it's cool / I be stirring up that money making music l.