Source : WordNet®

file system
     n : a system of classifying into files (usually arranged
         alphabetically) [syn: {filing system}]

Source : Free On-Line Dictionary of Computing

file system
     
         (FS, or "filesystem") 1. A system for
        organizing {directories} and {files}, generally in terms of
        how it is implemented in the {disk operating system}.  E.g.,
        "The {Macintosh file system} is just dandy as long as you
        don't have to interface it with any other file systems".
     
        2. The collection of files and directories stored on a given
        drive (floppy drive, hard drive, disk {partition}, {logical}
        drive, {RAM drive}, etc.).  E.g., "mount attaches a named file
        system to the file system hierarchy at the pathname location
        directory [...]" -- {Unix manual page} for "mount(8)".
     
        As an extension of this sense, "file system" is sometimes used
        to refer to the representatation of the file system's
        organisation (e.g. its {file allocation table}) as opposed the
        actual content of the files in the file system.
     
        {Unix manual page}: fs(5), mount(8).
     
        (1997-04-10)