Yes, you are right. ACP means "Automatic Colt Pistol", and is a term generally applied in the U.S. to ammunition designed to be fired in one of the Colt-made versions of a Jonathan Browning designed pistol, (most often the .45). Such calibers were often called "Browning" when made in Europe. The term "parabellum" is a Latin phrase meaning "for war", and was applied to the 9mm ammunition intended for use in the German P '08, the 9mm military caliber Luger pistol adopted by Germany in 1908. To the best of my knowledge, this term was never applied to any other cartridge.

Keep yore powder dry!!