1. A surface forming a common boundary between adjacent regions, bodies, substances, or phases.
2. A point at which independent systems or diverse groups interact: "the interface between crime and politics where much of our reality is to be found" (Jack Kroll).
3. Computer Science
   1. The point of interaction or communication between a computer and any other entity, such as a printer or human operator.
   2. The layout of an application's graphic or textual controls in conjunction with the way the application responds to user activity: an interface whose icons were hard to remember.

1. To join by means of an interface.
2. To serve as an interface for.

1. To serve as an interface or become interfaced.
2. To interact or coordinate smoothly: "Theatergoers were lured out of their seats and interfaced with the scenery" (New York Times).

Usage Note: The noun interface has been around since the 1880s, meaning "a surface forming a common boundary, as between bodies or regions." But the word did not really take off until the 1960s, when it began to be used in the computer industry to designate the point of interaction between a computer and another system, such as a printer. The word was applied to other interactions as well—between departments in an organization, for example, or between fields of study. Shortly thereafter interface developed a use as a verb, but it never really caught on outside its niche in the computer world, where it still thrives. The Usage Panel has been unable to muster much enthusiasm for the verb. Thirty-seven percent of Panelists accept it when it designates the interaction between people in the sentence The managing editor must interface with a variety of freelance editors and proofreaders. But the percentage drops to 22 when the interaction is between a corporation and the public or between various communities in a city. Many Panelists complain that interface is pretentious and jargony. Certainly, it has no shortage of acceptable synonyms; cooperate, deal, exchange information, interact, and work present themselves as ready substitutes.

1. The point of interaction or communication between a computer and any other entity, such as a printer or human operator.
2. The layout of an application's graphic or textual controls in conjunction with the way the application responds to user activity. See more at GUI.