WordNet (r) 3.0 (2006):

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, descriptor]
    2: a piece of stored information that is used to identify an
       item in an information storage and retrieval system

The Free On-line Dictionary of Computing (30 December 2018):

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)