Acronym for Portable Operating System Interface for UNIX, a set of IEEE and ISO standards that define an interface between programs and operating systems. By designing their programs to conform to POSIX, developers have some assurance that their software can be easily ported to POSIX-compliant operating systems. This includes most varieties of UNIX.
The POSIX standards are now maintained by an arm of the IEEE called the Portable Applications Standards Committee (PASC).
