a military rifle capable of both automatic and semiautomatic fire, utilizing an intermediate-power cartridge.
a nonmilitary weapon modeled on the military assault rifle, usually modified to allow only semiautomatic fire.
Origin of assault rifle
First recorded in 1970–75
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for assault rifle
mainly US a semiautomatic firearm with additional features such as a large magazine, a bayonet fitting, etc
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012