The "AR" in AR-15 stands for assault rifle.
As mass shootings have become a disturbingly regular occurrence in the United States, so too have heated discussions about the weapon used in many of the worst incidents of the past decade, AR-15 firearms and their offshoots. Discussions about guns in America tend to be politically fraught, and so too is the terminology surrounding them.
A frequent misconception about AR-15 firearms, for instance, is that the “AR” in the name stands for “assault rifle.” It does not. AR stands for ArmaLite Rifle, reflecting the company name (ArmaLite) of the original manufacturer of the weapon. Although ArmaLite sold the design of the rifle to Colt in 1959, the term “AR-15” has persisted and acts as a catch-all for similar guns, even though various models with different manufacturers have different names.
ArmaLite developed the weapon in the 1950s with the original intention that it would be used by the military but didn’t have much success selling it before handing it off to Colt. As NPR reports, Colt had widespread success selling the automatic M-16 to the military, which troops used in Vietnam. Colt produced a semi-automatic, civilian version of that weapon and marketed it as the “AR-15.”
“When Colt’s patents for the AR-15 expired in the 1970s, other manufacturers began making similar models,” NPR reported. “Those gun makers gave the weapons their own names, yet the popularity of the AR-15 turned it into a generic term for all types of AR-15-style rifles.”