a weapon, as a pistol or sword, carried at the side or in the belt.
Origin of side arm
First recorded in 1680–90
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
weapons carried on the person, by sling, belt, or holster, such as a sword, pistol, 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