means the shared boundary or point of interaction where two systems, devices, or people meet and communicate.

from A 19th-century scientific coinage stitched from Latin inter- ('between') and 'face' (from Latin facies, 'form, appearance'). It first named the physical surface where two phases or substances met — like the boundary between oil and water. The computing sense, where humans meet machines, didn't arrive until the mid-20th century, borrowing that same image of a meeting-place between two different worlds.