The short answer: the word “hamburger” came from Hamburg, Germany.
Hamburger began with the Tatars (or Tartars), a nomadic people who conquered central Asia and eastern Europe in the Middle Ages. The Tatars consumed their shredded beef raw. According to one account, the Tatars tenderized their beef by putting it between the saddle and the horse as they rode. When the Tatars introduced this food to Germany, the beef was mixed with local spices and fried or broiled and became known as Hamburg steak. German emigrants to the United States brought Hamburg steak with them. It showed up on New York restaurant menus in the 1880s. Hamburgers became a sensation as sandwiches at the 1904 World’s Fair in St. Louis.