Link to mapping glossary entry in "Mapping Types - dict" and os.environ docs.
diff --git a/Doc/library/os.rst b/Doc/library/os.rst
index 410e03a..9429810 100644
--- a/Doc/library/os.rst
+++ b/Doc/library/os.rst
@@ -98,7 +98,7 @@
.. data:: environ
- A mapping object representing the string environment. For example,
+ A :term:`mapping` object representing the string environment. For example,
``environ['HOME']`` is the pathname of your home directory (on some platforms),
and is equivalent to ``getenv("HOME")`` in C.
@@ -138,7 +138,7 @@
.. data:: environb
- Bytes version of :data:`environ`: a mapping object representing the
+ Bytes version of :data:`environ`: a :term:`mapping` object representing the
environment as byte strings. :data:`environ` and :data:`environb` are
synchronized (modify :data:`environb` updates :data:`environ`, and vice
versa).