.357 /ˈθɹiː fɪftiː ˈsɛvən/ noun2 •.357 Magnum (a class of firearm cartridge). •A firearm chambered for .357 Magnum cartridges.Estimates of the total population of on duty handguns in the U.S. showed 70 percent of all officers using .38s and 25 percent using .357s. — 1977 forms.357s
