A firearm is a weapon that launches one or more projectile(s) at high velocity through confined burning of a propellant.
fire·arm
A weapon, especially a pistol or rifle, capable of firing a projectile and using an explosive charge as a propellant.
Firearm - definition of firearm by The Free Dictionary
Webster
fire·arm
: a weapon from which a shot is discharged by gunpowder —usually used of small arms
Firearm Definition & Meaning - Merriam-Webster
Not sure what there it to debate here, seems a pretty well established definition, only thing left in question are opinions.
I actually lol’ed when I saw his post.