A Kalashnikov is a kind of rifle — a long gun — that can fire very fast, one shot after another. It is named after Mikhail Kalashnikov, a Russian soldier and inventor (1919–2013) who designed it after the Second World War. The most famous model is the AK-47; in ordinary talk, “a Kalashnikov” often just means that family of guns, not one special museum piece. They became common because they are relatively cheap, simple to learn, and keep working when they are dirty or roughly treated. Armies have used them, and so have fighters in many wars, so the name in the news is often a shorthand for that whole style of assault rifle. It is a proper name turned into a thing-name: like saying “a Ford” for a car.