WordNet (r) 3.0 (2006):

garbage collection
    n 1: the collection and removal of garbage [syn: garbage
         collection, garbage pickup, trash collection, trash
         pickup]

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

garbage collection
garbage collect

    (GC) The process by which dynamically allocated
   storage is reclaimed during the execution of a program.  The
   term usually refers to automatic periodic storage reclamation
   by the garbage collector (part of the run-time system), as
   opposed to explicit code to free specific blocks of memory.

   Automatic garbage collection is usually triggered during
   memory allocation when the amount free memory falls below some
   threshold or after a certain number of allocations.  Normal
   execution is suspended and the garbage collector is run.
   There are many variations on this basic scheme.

   Languages like Lisp represent expressions as graphs built
   from cells which contain pointers and data.  These languages
   use automatic dynamic storage allocation to build
   expressions.  During the evaluation of an expression it is
   necessary to reclaim space which is used by subexpressions but
   which is no longer pointed to by anything.  This reclaimed
   memory is returned to the free memory pool for subsequent
   reallocation.

   Without garbage collection the program's memory requirements
   would increase monotonically throughout execution, possibly
   exceeding system limits on virtual memory size.

   The three main methods are mark-sweep garbage collection,
   reference counting and copying garbage collection.

   See also the AI koan about garbage collection.

   (1997-08-25)