application server
1. <software> A designer's or developer's suite of software that helps programmers isolate the business logic in their programs from the platform-related code. Application servers can handle all of the application logic and connectivity found in client-server applications. Many application servers also offer features such as transaction management, clustering and failover, and load balancing; nearly all offer ODBC support.
Application servers range from small footprint, web-based processors for intelligent appliances or remote embedded devices, to complete environments for assembling, deploying, and maintaining scalable multi-tier applications across an enterprise.
2. <software> Production programs run on a mid-sized computer that handle all application operations between browser-based computers and an organisation's back-end business applications or databases. The application server works as a translator, allowing, for example, a customer with a browser to search an online retailer's database for pricing information.
3. <hardware> The device on which application server software runs. Application Service Providers offer commercial access to such devices.
Citrix Application Serving White Paper.
Application Server Sites, a list maintained by Vayda & Herzum.