diff --git a/doc/glossary.rst b/doc/glossary.rst
index f989df1ae..ca12067c4 100644
--- a/doc/glossary.rst
+++ b/doc/glossary.rst
@@ -73,9 +73,12 @@ Glossary
 
      For more information, refer to :doc:`/usage/extensions/index`.
 
-   root document
+   master document
       The document that contains the root :rst:dir:`toctree` directive.
 
+   root document
+      Same as :term:`master document`.
+
    object
       The basic building block of Sphinx documentation.  Every "object
       directive" (e.g. :rst:dir:`function` or :rst:dir:`object`) creates such a