What does POSIX stand for?

Portable Operating System-9 - Military technology (DDF)

Portable Operating System based on Unix (SAUS)

Portable Operating System Interface Exchange

Portable Operating System Interface eXtensions

Portable Operating System Interface for Computer Environments (AAGC)

Portable Operating System Interface for Computer Systems (SAUS)

Portable Operating System Interface for Unix - Computer science

Portable Operating System Interface for X (SAUS)

Portable Operating Systems for Computer Environments (AD)

Portable Operating System Specification - IEEE