1. Alternatively known as an Apple Event, Interapplication communications (IAC) is the method of how the Apple Macintosh and software programs on the Apple Macintosh communicate with one another.
2. IAC is also shorthand for In Any Case, IAC is an acronym used in chat rooms and message boards. Below is an example of how this could be user in chat.
IAC I really think you should still go see that movie.