DOCS-14322 v5.0 backport (#257)

Author: ianf-mongodb

source/reference/glossary.txt

@@ -941,6 +941,12 @@ Glossary
       :doc:`/core/storage-engines` for specific details on the built-in
       storage engines in MongoDB.
 
+   Subject Alternative Name
+      Subject Alternative Name (SAN) is an extension of the X.509 
+      certificate which allows an array of values such as IP addresses 
+      and domain names that specify which resources a single security 
+      certificate may secure.
+
    strict consistency
       A property of a distributed system requiring that all members
       always reflect the latest changes to the system. In a database