ARBYS stands for American Roast Beef Youngstown Style. Advertisement: This definition appears very rarely. Other Resources: Acronym Finder has 1 verified definitions for ARBYS. Tweet. They confirmed there’s absolutely no truth the story, and said that their roast beef is, in fact, completely beef. also How much is a pound of Arbys roast beef? All three meats are sliced at the restaurant and cost roughly the same as sliced deli meat at a grocery store: $4.99 for a half pound.