American-Heritage dictionary said:burg·er audio (bûrgr) KEY
NOUN:
1. A sandwich consisting of a bun, a cooked beef patty, and often other ingredients such as cheese, onion slices, lettuce, or condiments. Often used in combination: a cheeseburger.
2. A similar sandwich with a nonbeef filling. Often used in combination: a crab burger; a tofu burger.