diff --git a/user_manual/groupware/sync_thunderbird.rst b/user_manual/groupware/sync_thunderbird.rst
index 627a34c7b..5d1a9893b 100644
--- a/user_manual/groupware/sync_thunderbird.rst
+++ b/user_manual/groupware/sync_thunderbird.rst
@@ -73,7 +73,7 @@ Alternative: Using the CardBook add-on (Contacts only)
 
    .. image:: ../images/addressbook_name.png
 
-#. When you are finished, CardBook synchronizes your address books. You can always trigger a synchroniZation manually by clicking "Synchronize" in the top left corner of CardBook:
+#. When you are finished, CardBook synchronizes your address books. You can always trigger a synchronization manually by clicking "Synchronize" in the top left corner of CardBook:
 
    .. image:: ../images/synchronize_cardbook.png