diff --git a/source/reference/glossary.txt b/source/reference/glossary.txt
index 905bd9f6e97..57e7d137109 100644
--- a/source/reference/glossary.txt
+++ b/source/reference/glossary.txt
@@ -366,10 +366,6 @@ Glossary
       migration of :term:`chunks <chunk>`. Administrators must disable
       the balancer for all maintenance operations on a sharded cluster.
 
-   fsync
-      A system call that flushes all dirty, in-memory pages to disk. MongoDB
-      calls ``fsync()`` every 60 seconds.
-
    chunk
       In the context of a :term:`sharded cluster`, a chunk is a contiguous
       range of :term:`shard key` values assigned to a particular :term:`shard`.
@@ -588,10 +584,11 @@ Glossary
       nodes have :term:`eventual consistency`.
 
    write concern
-      A setting on writes to MongoDB that allows the user to specify,
-      how the database will handle a write operation before
-      returning. This often determines how many :term:`replica set`
-      members should propagate a write before returning.
+      Specifies whether a write operation has succeeded. Write concern
+      allows your application to detect insertion errors or unavailable
+      :program:`mongod` instances. For :term:`replica sets <replica
+      set>`, you can configure write concern to confirm replication to a
+      specified number of members.
 
       .. seealso:: :ref:`Write Concern for Replica Sets <replica-set-write-concern>`.