The Jargon File (version 4.4.7, 29 Dec 2003):

dangling pointer
 n.

    [common] A reference that doesn't actually lead anywhere (in C and some
    other languages, a pointer that doesn't actually point at anything valid).
    Usually this happens because it formerly pointed to something that has
    moved or disappeared. Used as jargon in a generalization of its techspeak
    meaning; for example, a local phone number for a person who has since moved
    to the other coast is a dangling pointer.


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

dangling pointer

    A reference that doesn't actually lead anywhere.
   In C and some other languages, a pointer that doesn't
   actually point at anything valid.  Usually this happens
   because it formerly pointed to something that has moved or
   disappeared, e.g. a heap-allocated block which has been freed
   and reused.

   Used as jargon in a generalisation of its technical meaning;
   for example, a local phone number for a person who has since
   moved is a dangling pointer.

   This dictionary contains many dangling pointers -
   cross-references to non-existent entries, as explained in the
   Help page (help.html).

   [Jargon File]

   (2014-09-20)