gh-150831: clarify generator, generator function, and generator iterator in glossary

Doc/glossary.rst

@@ -641,23 +641,33 @@ Glossary
       .. index:: single: generator
 
    generator
-      A function which returns a :term:`generator iterator`.  It looks like a
-      normal function except that it contains :keyword:`yield` expressions
-      for producing a series of values usable in a for-loop or that can be
-      retrieved one at a time with the :func:`next` function.
+      Informally used to mean either a :term:`generator function` or a
+      :term:`generator iterator`, depending on context.  The formal terms
+      :term:`generator function` and :term:`generator iterator` are uncommon
+      in practice; "generator" alone is almost always sufficient.
+
+      .. index:: single: generator function
 
-      Usually refers to a generator function, but may refer to a
-      *generator iterator* in some contexts.  In cases where the intended
-      meaning isn't clear, using the full terms avoids ambiguity.
+   generator function
+      A function which returns a :term:`generator` object.  It looks like a
+      normal function except that it contains :keyword:`yield` expressions
+      for producing a series of values usable in a :keyword:`for`\-loop or
+      that can be retrieved one at a time with the :func:`next` function.
+      See :pep:`255`.
 
    generator iterator
-      An object created by a :term:`generator` function.
+      An object created by a :term:`generator function` or a
+      :term:`generator expression`.
 
       Each :keyword:`yield` temporarily suspends processing, remembering the
-      execution state (including local variables and pending
-      try-statements).  When the *generator iterator* resumes, it picks up where
-      it left off (in contrast to functions which start fresh on every
-      invocation).
+      execution state (including local variables and pending try-statements).
+      When the *generator iterator* resumes, it picks up where it left off
+      (in contrast to functions which start fresh on every invocation).
+
+      Generator iterators also implement the :meth:`~generator.send` method
+      to send a value into the suspended generator, and the
+      :meth:`~generator.throw` method to raise an exception at the point
+      where the generator was paused.  See :pep:`342`.
 
       .. index:: single: generator expression