interface (I/F)
1. In a system , a shared boundary, i.e., the boundary between two subsystems or two devices.
2. A shared boundary between two functional units, defined by specific attributes, such as functional characteristics, common physical interconnection characteristics, and signal characteristics.
3. A point of communication between two or more processes, persons, or other physical entities.
4. A point of interconnection between user terminal equipment and commercial communications facilities.
5. To interconnect two or more entities at a common point or shared boundary.
6. [A] common boundary between independent systems or modules where interactions take place. [INFOSEC-99]
7. The point of interconnection between two distinct but adjacent communications systems having different functions. The interface in the communication-satellite service is that point where communications terminal equipment of the terrestrial common carriers or other authorized entities interconnects with the terminal equipment of the communication-satellite earth station complex. The interface in the communication-satellite service shall be located at the earth station site, or if this is impracticable, as close thereto as possible. [47CFR]
8. The shared boundary between two functional units, defined by functional characteristics and other characteristics, as appropriate [POSIX.0].