Noun: the connection between two applications or hardware devices, which facilitates data exchange. An interface can include hardware, software and can take place using similar or different categories of data. Verb: to make an appropriate physical connection between two pieces of hardware so that the equipment can communicate or work together effectively.
This can be the plug or cable that links the PC to the modem, or software that connects text with tables, or even the keyboard, which acts as an interface between computer and user.