Add :term:s for "new-style class".
diff --git a/Doc/tutorial/classes.rst b/Doc/tutorial/classes.rst
index d5bde44..e4e8451 100644
--- a/Doc/tutorial/classes.rst
+++ b/Doc/tutorial/classes.rst
@@ -495,8 +495,8 @@
:class:`Base2`. The depth-first rule makes no differences between direct and
inherited attributes of :class:`Base1`.)
-For new-style classes, the method resolution order changes dynamically to
-support cooperative calls to :func:`super`. This approach is known in some
+For :term:`new-style class`\es, the method resolution order changes dynamically
+to support cooperative calls to :func:`super`. This approach is known in some
other multiple-inheritance languages as call-next-method and is more powerful
than the super call found in single-inheritance languages.