Source : WordNet®

descriptor
     n 1: the phonological or orthographic sound or appearance of a
          word that can be used to describe or identify something;
          "the inflected forms of a word can be represented by a
          stem and a list of inflections to be attached" [syn: {form},
           {word form}, {signifier}]
     2: a piece of stored information that is used to identify an
        item in an information storage and retrieval system

Source : Free On-Line Dictionary of Computing

descriptor
     
         An integer, string or other small data
        value which refers to one of several objects allocated to a
        program by the {operating system}, usually the {kernel}.  A
        common example is a {Unix} {file descriptor} which is a small
        integer that identifies an I/O channel.  Another example is a
        reference to an area of memory (e.g. {shared memory}).
     
        Compare {capability}.
     
        (1998-02-06)