rag·top (răg′tŏp′) n. Slang A convertible automobile. ragtop (ˈræɡˌtɒp) n 1. (Automotive Engineering) a. a vehicle roof made of fabric, which can be folded back or removed b. (as modifier): a ragtop roadster. 2. (Automotive Engineering) (as modifier): a ragtop roadster. 3. (Automotive Engineering) a vehicle with a ragtop.