let the term be linked
diff --git a/Doc/library/abc.rst b/Doc/library/abc.rst
index 9cdb5b3..8700faf 100644
--- a/Doc/library/abc.rst
+++ b/Doc/library/abc.rst
@@ -9,8 +9,8 @@
.. versionadded:: 2.6
-This module provides the infrastructure for defining :term:`abstract base
-classes` (ABCs) in Python, as outlined in :pep:`3119`; see the PEP for why this
+This module provides the infrastructure for defining an :term:`abstract base
+class` (ABCs) in Python, as outlined in :pep:`3119`; see the PEP for why this
was added to Python. (See also :pep:`3141` and the :mod:`numbers` module
regarding a type hierarchy for numbers based on ABCs.)