1. (chemistry) a surface forming a common boundary between two things (two objects or liquids or chemical phases)
2. (computer science) a program that controls a display for the user (usually on a computer monitor) and that allows the user to interact with the system
3. the overlap where two theories or phenomena affect each other or have links with each other;
"the interface between chemistry and biology"
4. (computer science) computer circuit consisting of the hardware and associated circuitry that links one device with another (especially a computer and a hard disk drive or other peripherals)