The problem is English, and how it used, and misused
And also the belief that dictionaries give correct and proper definitions of technical terms. They don't. And they say so, they give definitions of words as found in "popular usage". Whether that is correct in technical terms is apparently of no concern.
Having lived through most of the evolution of the term, here is a brief history of the terms "assault rifle", and "assault weapon". We went through this in 94, and for those who weren't around then, here is is, again...
In 1943 German designers created and fielded small numbers of a new kind of firearm. It was selective fire (meaning it would fire semi auto or full auto with the flip of a switch or the push of a button), and it fired a round that was more powerful than the regular pistol round, but not as powerful as the standard infantry rifle round.
There was a standing order from Hitler that no resources be wasted on the developement of a new rifle, but developement of new submachine guns was allowed. SO, the new gun was called a submachinegun (Maschinen Pistole or MP in German) The MP43 was field tested in small numbers, and was very well recieved by the troops. So was its follow on model, the MP44. Hitler was not aware of the new rifle for some time, and when he found out his orders had been flouted, he was furious.
After a demonstration, he changed his mind, and supported it, giving the gun the name Sturmgewehr ("Assault rifle" in German). The German word Sturm is translated into English as either "assault" (in the military sense, assaulting or storming an objective) OR as "storm" (in the weather sense). Which translation is correct depends on the context.
For several decades after WWII, the shooting community, both in and out of the military used the term "assault rifle" for arms that had the same functionality as the original German Sturmgewehr. The key features necessary to meet the definition were selective fire and an "intermediate power" cartridge. Many other features were common to most of the assault rifle designs (such as pistol grips, detacable magazines, straight line stocks, etc...) but if it wasn't select fire and intermediate power cartridge, it wasn't considered a true assault rifle. Now, this term was never an officially adopted term by our military or govt, but in was in general use in the shooting community.
Fast forward to the 1980s, and there begin some highly publicised mass shootings (where the shooter was killed, or killed themself, leaving nothing but the gun used to focus on). The guns used were civilan legal semi automatic only versions of submachine gun (San Ysidro Mac Donalds shooting), and an AK47 (Stockton school shooting).
These masacres (and in particularly the Stockton school shooting) ignighted a storm of emotions. The anti gun faction began calling the guns "assault rifles", and the medi picked right up on it.
We cried, "NO, they are not assault rifles! They are not assault rifles because they do not shoot full automatic! They only look like assault rifles on the outside!" As usual, the truth did little good.
Since they had been caught not using the right teminology, the media did the right thing (sort of) and began calling them "semi-automatic assault rifles".
This very quickly proved to be a very cumbersome sound bite, and so they coined the term "assault weapon" to refer to any and all the guns with "military" style features. The politicians codified a defintion in law in the 1994 AWB, and several states virtually copied it.
It defined "assault weapon" as semi automatic firearms (rifle, pistol or shotgun) with a certain number of specific features. Pistol grip, detatchable magazine, bayonet lug, flash suppressor, etc,...
Under US law, real "assault rifles", being select fire, are legally machine guns, and regulated as such under the NFA 1934.
Assault Weapons in legal defintion are semi autos with certain cosmetic features.
Sadly, arguing the differences, even the fact that the press isn't even accurately using their own made up terms, doesn't get us far with the bulk of the un or under informed public.
Those people who argue that an "assault weapon" is any weapon used to assault someone are using the term in the wrong context.