Source : Free On-Line Dictionary of Computing

rc file
     
        /R C fi:l/ [Unix: from the startup script "/etc/rc", but this
        is commonly believed to have been named after older scripts to
        "run commands"] Script file containing startup instructions
        for an application program (or an entire operating system),
        usually a text file containing commands of the sort that might
        have been invoked manually once the system was running but are
        to be executed automatically each time the system starts up.
        See also {dot file}, {profile} (sense 1).
     
        [{Jargon File}]