Demon

 DEMON (dee'mun) n. A portion of a program which is not invoked
       explicitly, but which lays dormant waiting for some condition(s) to
       occur. See DAEMON. The distinction is that demons are usually
       processes within a program, while daemons are usually programs running
       on an operating system. Demons are particularly common in AI programs.
       For example, a knowledge manipulation program might implement
       inference rules as demons. Whenever a new piece of knowledge was
       added, various demons would activate (which demons depends on the
       particular piece of data) and would create additional pieces of
       knowledge by applying their respective inference rules to the original
       piece. These new pieces could in turn activate more demons as the
       inferences filtered down through chains of logic. Meanwhile the main
       program could continue with whatever its primary task was.