Refers to programs that connect two separate applications. MiddleWare is often used as the glue between a database and web-based application. Sometimes referred to as plumbing.
software components in a distributed system that form a middle tier of processing between client applications interfacing with users and backend components such as databases or application servers
Middleware is a layer of software that runs on top of a set top box operating system which allows application software to be run over a wide variety of set top boxes. Examples of set-top middleware include Liberate and OpenTV.