Definitions for handgunˈhændˌgʌn
Random House Webster's College Dictionary
any firearm that can be held and fired with one hand; a revolver or a pistol.
Origin of handgun:
pistol, handgun, side arm, shooting iron(noun)
a firearm that is held and fired with one hand
Kernerman English Learner's Dictionary
a small gun
A small, hand-held gun with a relatively short barrel.
Origin: From hand + gun.