Source : WordNet®

unzip
     v : open the zipper of; "unzip the bag" [ant: {zip up}]
     [also: {unzipping}, {unzipped}]

Source : Free On-Line Dictionary of Computing

unzip
     
        1.  To extract files from an archive
        created with {PKWare}'s {PKZIP} archiver.
     
        2.  A program to list, test, or extract
        files from a {ZIP} archive, commonly found on {MS-DOS}
        systems.  zip, creates ZIP archives; both programs are
        compatible with archives created by {PKWARE}'s {PKZIP} and
        {PKUNZIP} for {MS-DOS}.
     
        (1995-03-06)