Source : Webster's Revised Unabridged Dictionary (1913)

Folder \Fold"er\, n.
   One who, or that which, folds; esp., a flat, knifelike
   instrument used for folding paper.

Source : WordNet®

folder
     n 1: a small book usually having a paper cover [syn: {booklet}, {brochure},
           {leaflet}, {pamphlet}]
     2: covering that is folded over to protect the contents

Source : Free On-Line Dictionary of Computing

folder
     
         A {directory} in the sense of a collection
        of computer {files}.  The term is more common in systems such
        as the {Macintosh} or {Windows 95} which have a {graphical
        user interface} and provide a graphical {file browser} in
        which directories are traditionally depicted as folders (like
        small briefcases).
     
        (1997-03-20)