9mmP is short for 9×19mm Parabellum .
The 9×19mm Parabellum ( abbreviated 9mm , 9×19mm or 9×19 ) cartridge was designed by Georg Luger and introduced in 1902 by the German weapons manufacturer Deutsche Waffen- und Munitionsfabriken ( DWM ) for their Luger semi-automatic pistol .
9×19mm Parabellum