The person who coined the term "assault rifle" was a professional anti-gunner named Josh Sugarmann.
No, sorry, he didn't. The person who coined the term "assault rifle" was Adolf Hitler, in 1944.
Because earlier in the war, when Germany was winning, Hitler had forbidden the development of new rifles as a "waste of resources", the German engineers working on the concept continued their work under the cover name of MP
(maschinen pistole) the German term for submachine guns, development of which was not forbidden. When he found out about the "new rifles" Hitler was furious, but after having some demonstrated for him, changed his mind and became enthusiastic about them, renaming the MP-44 the
Sturmgewehr.
Sturmgewehr translates to "assault rifle" in English.
After the war, the firearms community adopted the term "assault rifle" and defined it using the primary features found on the German gun. And those were Selective fire (semi AND full auto) box magazine fed, intermediate power cartridge. Other features like a straight line stock and separate pistol grip are common but not required to meet the definition of assault rifle.
What Sugermann did, after leaving NBC over some pickup trucks being rigged to blow up, was jump into the gun control "market" and while I don't know if he, personally, coined the term "assault weapon" or not, but he did push hard for its use in the media cynically aware that the similarity in terms would confuse the public into thinking assault weapons were machine guns and so getting restrictions and bans was made easier.
If it is an "assault weapon" and its a rifle, people who don't know (or care) about the correct definition call it an assault rifle.
By the definition if the 1994 federal law, assault weapons are semi automatic rifles, pistols and shotguns that possess features listed in that law.
Note that, SEMI AUTOMATIC. NO actual assault rifle is covered under that law. Not one. Under Federal law, assault rifles are machine guns, due to the capacity to fire full auto.
Sugarmann embraced and promoted deceptive and misleading terminology about firearms to advance his agenda, and isn't on my list of honorable opponents over gun control.