API

From DmWiki

An 'Application Programming Interface'. It is generally the range of function calls that the developer uses to interface with a library such as OpenGL or DirectX. These are quite specific to the library itself, and thus the documentation of the library should be consulted for help.

Term API also applies to Application Programming Interfaces which are operating system dependant, like Windows API.

More info on API (http://blog.eukhost.com/2006/11/27/application-program-interfaceapi/)