Quote Originally Posted by AntRobertson View Post
Here you go: GunFax.com - the unofficial Calico fan site and Rockin' Rimfires

The exact etymology of the term "assault rifle / weapon" is unclear but what is not disputed is that it arose during World War II with the Sturmgewehr 44 - i.e. almost 80 years ago. Further, as you can see in that link above, the US Army was using and defined the term in 1970 (if not even earlier) in Army intelligence document FSTC-CW-07-03-70.

I found this out with literally a 2 min Google search.
From your link
It states, “Assault rifles are short, compact, selective-fire weapons that fire a cartridge intermediate in power between submachine gun and rifle cartridges.
So an AR-15, being just a semi-automatic civilian rifle, is not an “assault rifle,” nor is it “high-powered” since its typical 5.56x45mm chambering is a medium-powered cartridge.