hamburger - A hamburger (or simply a burger) is a sandwich that consists of a cooked patty made of ground meat and is generally served with various garnish or condiments like ketchup, mustard, mayonnaise, lettuce, tomato, onion, relish pickles, and cheese toppings, placed inside a sliced Hamburger bun, often baked specially for this purpose, or pieces of bread or toast. The meat patty is beef, unless otherwise noted.