Add more entries to the glossary.
Written by Jeff Wheeler for GHOP.
diff --git a/Doc/library/weakref.rst b/Doc/library/weakref.rst
index 225991a..7d9c588 100644
--- a/Doc/library/weakref.rst
+++ b/Doc/library/weakref.rst
@@ -22,22 +22,22 @@
by a weak reference.
A weak reference to an object is not enough to keep the object alive: when the
-only remaining references to a referent are weak references, garbage collection
-is free to destroy the referent and reuse its memory for something else. A
-primary use for weak references is to implement caches or mappings holding large
-objects, where it's desired that a large object not be kept alive solely because
-it appears in a cache or mapping. For example, if you have a number of large
-binary image objects, you may wish to associate a name with each. If you used a
-Python dictionary to map names to images, or images to names, the image objects
-would remain alive just because they appeared as values or keys in the
-dictionaries. The :class:`WeakKeyDictionary` and :class:`WeakValueDictionary`
-classes supplied by the :mod:`weakref` module are an alternative, using weak
-references to construct mappings that don't keep objects alive solely because
-they appear in the mapping objects. If, for example, an image object is a value
-in a :class:`WeakValueDictionary`, then when the last remaining references to
-that image object are the weak references held by weak mappings, garbage
-collection can reclaim the object, and its corresponding entries in weak
-mappings are simply deleted.
+only remaining references to a referent are weak references,
+:term:`garbage collection` is free to destroy the referent and reuse its memory
+for something else. A primary use for weak references is to implement caches or
+mappings holding large objects, where it's desired that a large object not be
+kept alive solely because it appears in a cache or mapping. For example, if you
+have a number of large binary image objects, you may wish to associate a name
+with each. If you used a Python dictionary to map names to images, or images to
+names, the image objects would remain alive just because they appeared as values
+or keys in the dictionaries. The :class:`WeakKeyDictionary` and
+:class:`WeakValueDictionary` classes supplied by the :mod:`weakref` module are
+an alternative, using weak references to construct mappings that don't keep
+objects alive solely because they appear in the mapping objects. If, for
+example, an image object is a value in a :class:`WeakValueDictionary`, then when
+the last remaining references to that image object are the weak references held
+by weak mappings, garbage collection can reclaim the object, and its
+corresponding entries in weak mappings are simply deleted.
:class:`WeakKeyDictionary` and :class:`WeakValueDictionary` use weak references
in their implementation, setting up callback functions on the weak references