The Collaborative International Dictionary of English v.0.48:
beefburger \beef"burg*er\ n. a fried cake of minced beef served on a bun. Syn: hamburger. [WordNet 1.5]WordNet (r) 3.0 (2006):
beefburger n 1: a sandwich consisting of a fried cake of minced beef served on a bun, often with other ingredients [syn: hamburger, beefburger, burger]