It literally means ArmaLite Rifle after its original designer and manufacturer. At least verify your information prior to claiming it as fact.

The AR in AR-15 stands for Armalite Rifle. Armalite being the company that initially designed and manufactured it, though basically everyone has had a go at making a variant of it. You won't find the term "assault rifle" in significant use, at least not in English.

The AR-15 sold to the public cannot "spray." They are semi-automatic. One pull of the trigger, one bullet out of the barrel. Fully auto or burst fire modes aren't available to the general public; I believe a few made it into circulation but collectors tend to hang onto them. It's not a bullet hose.

There are a lot of rifles out there that have walnut stocks and such that look like grampa's huntin' gun that are functionally similar to an AR-15, ie same ease of operation, same capacity, same (relatively small) caliber, same rate of fire. But you don't seem to be afraid of those. So I can only assume you have a fear of black plastic. That's the main unique feature of the AR-15 compared to other semi-automatic rifles on the market, the stock is made of plastic rather than wood.

Here's the real truth: mass shootings in America are not caused by firearms engineering, and restricting features of firearms isn't going to solve the problem. A shooting is carried out with an AR-15. People start talking about banning AR-15s. Remember Columbine? That was actually a failed bombing, most of the killings were done with a TEC-9...what would you categorize that as? An open bolt pistol? A "That's not an Uzi?" and a shotgun. Well TEC-9s were banned. Sure stopped school shootings. Virginia Tech was done with pistols.

You want the problem solved? Work on reducing hopelessness in young men. People HATE that answer, because, well...people hate young men. But that's the answer.

This is factually incorrect. Don't take this as a judgement on you or your position, just that you should be approaching any side from a factually sound place.

"AR" in "AR-15" stands for ArmaLite Rifle. ArmaLite is the firearms manufacturer where Eugene Stoner was working when he designed the rifle.

Assault rifles, and most other weapons capable of automatic fire, are generally not intended to be used as "spray 'n pray" weapons. That is generally reserved for stationary machine guns (think the beach on D-Day).

Assault rifles generally are classified as weapons that fire an intermediary cartridge that are capable of select-fire. Meaning that they fire cartridges with size and energy in between centerfire pistol (ex. 9x19mm) and full-power rifle (ex. .30-06 Springfield AKA 7.62x73mm) and the operator may select between multiple modes of fire. Usually these are semi-automatic (one round per trigger pull), fully-automatic (continues to fire rounds while trigger is held down) and/or burst-fire (two to three rounds per trigger pull).

The use of fully-automatic fire on modern assault rifles is extremely limited, with standard issue military rifles in the US military having the fire mode completely absent until the recent switch from the M4 (semi-auto and burst-fire only) to the M4A1 (semi-auto and full-auto). Tactically, fully-automatic fire is usually limited in use to room clearing in close combat and for suppressing fire (keeping the enemy combatants from leaving cover) to allow the squad to break contact and retreat to safety. This is reflected in the types of units that have been consistently issued assault rifles capable of full-auto; generally special forces and reconnaissance units that may be deployed outside of range of friendly support.

Full-auto in an assault rifle is simply not very useful in modern military roles. A standard issue magazine holds 30 rounds. An M4A1 in full-auto fires about 800 rounds-per-minute. That means that it takes just a bit less than 2.5 seconds to empty an entire magazine, putting the soldier in the vulnerable position of needing to reload. In most situations, it's far better to employee a squad automatic weapon, which is generally fed by a belt with much higher capacity, allowing sustained suppressing fire to allow allies to maneuver.

All of that said, I do, personally, agree that civilians (including police forces) ought not to have military-like firearms primarily intended for shooting humans. But that is because I am mostly a pacifist. The ArmaLite Rifle (AR-15) is NOT a select-fire rifle but a semi-auto one. It can, however, be modified into one (illegally) and uses the same rounds and accessories. To me, that makes it "military-like" and should likely be heavily regulated (but won't be).

TL;DR - Whichever side you are arguing, do it with facts.