1. The part that is left over after something has been removed; remainder. 2. That or those remaining: The beginning was boring, but the rest was interesting. The rest are arriving later.
A REST API is an application programming interface (API) that conforms to the design principles of the representational state transfer (REST) architectural style, a style used to connect distributed hypermedia systems. REST APIs are sometimes referred to as RESTful APIs or RESTful web APIs.