diff --git a/Doc/library/sets.rst b/Doc/library/sets.rst
index 7bd29311402..a7ae3abdbe3 100644
--- a/Doc/library/sets.rst
+++ b/Doc/library/sets.rst
@@ -76,7 +76,8 @@ operations:
 +-------------------------------+------------+---------------------------------+
 | Operation                     | Equivalent | Result                          |
 +===============================+============+=================================+
-| ``len(s)``                    |            | cardinality of set *s*          |
+| ``len(s)``                    |            | number of elements in set *s*
+|                               |            | (cardinality)                   |
 +-------------------------------+------------+---------------------------------+
 | ``x in s``                    |            | test *x* for membership in *s*  |
 +-------------------------------+------------+---------------------------------+
diff --git a/Doc/library/stdtypes.rst b/Doc/library/stdtypes.rst
index fb9140d6c52..91d89f15ed6 100644
--- a/Doc/library/stdtypes.rst
+++ b/Doc/library/stdtypes.rst
@@ -1779,7 +1779,7 @@ The constructors for both classes work the same:
 
    .. describe:: len(s)
 
-      Return the cardinality of set *s*.
+      Return the number of elements in set *s* (cardinality of *s*).
 
    .. describe:: x in s