From the SAP Terminology Guide:
A composite application is "An application that reuses, integrates, and orchestrates Web services to support business processes or specific user experiences. (Source: industry term.) Synonyms include: composite(s).
Composite applications are a kind of software application built from services. Composite applications are made possible by service-oriented architecture. Services used by composite applications are provided by service providers. A composite applications is sometimes referred to as a service consumer. A composite application may combine services from several service providers.
To create a composite application, a developer looks at all of the services available and then combines them, frequently using model-driven development techniques to create a new application. SAP has created many tools for helping to create composite applications such as SAP NetWeaver Visual Composer and the SAP Composite Application Framework.
Composite applications play a key role in expanding automation to meet new requirements. Previous generations of enterprise applications offered user interfaces, configuration through templates, settings, and other mechanisms, and programming APIs to allow the functionality to be extended. In SOA, the business objects inside a service provider are exposed through services so they can be recombined to meet new requirements.
- Composite Application defined in Wikipedia.