Source : Free On-Line Dictionary of Computing

hexit
     
         /hek'sit/ A {hexadecimal} digit (0-9, and A-F or
        a-f).  Used by people who claim that there are only *ten*
        digits, sixteen-fingered human beings being rather rare,
        despite what some keyboard designs might seem to imply (see
        {space-cadet keyboard}).
     
        [{Jargon File}]
     
        (1996-03-09)