Actually... You’re the one making the error. The .45 is called the “.45 automatic” and “ACP” stands for Automatic Colt Pistol. Nobody calls it the 1911 “semi-auto”.
The distinction between full and semi auto are about the type of weapon, but the name of the pistol is still just “automatic”. It is needlessly trivial to insist on the semi designation for every auto loading pistol. It refers to the way the mechanism self-loads with every shot. All self-loading pistols are commonly referred to as “autos”.
Ok. I’ll concede the semantics (my apologies, Mr. K). I make the distinction because so many people do not understand the difference. I recall being in a class at Gunsite and hearing Jeff Cooper make a similar distinction. The non-gun people think that an “automatic” is a machine pistol, not a semi-auto loader.
Just like the difference between a magazine and a clip.