the.com/gunman

means A man who carries out violence using a firearm, especially someone who attacks, robs, or kills with a gun.

from A plain compound of 'gun' plus 'man,' coined in the 1800s — no hidden story here, just blunt English stacking a weapon onto a person. 'Gun' itself traces back to medieval siege engines, oddly once a woman's name ('Gunilda' given to a catapult or cannon), before settling onto firearms. 'Gunman' followed the same straightforward path as 'swordsman' or 'rifleman' — name the weapon, add the wielder.