9 milli Share definition Flag A 9 millimeter pistol,refering to the diamater of the bottom of the round,common pistol among thugs,criminals,and various forms of street life Had to pull out my 9 milli and blast that blue jay 9 milli by Wolven March 28, 2003 0 0 Get merch Get the 9 milli mug. Buy Now — $32.95 See more merch