diff --git a/Documentation/SubmittingPatches b/Documentation/SubmittingPatches
index b0d0043..a417b25 100644
--- a/Documentation/SubmittingPatches
+++ b/Documentation/SubmittingPatches
@@ -363,7 +363,8 @@
 The "summary phrase" in the email's Subject should concisely
 describe the patch which that email contains.  The "summary
 phrase" should not be a filename.  Do not use the same "summary
-phrase" for every patch in a whole patch series.
+phrase" for every patch in a whole patch series (where a "patch
+series" is an ordered sequence of multiple, related patches).
 
 Bear in mind that the "summary phrase" of your email becomes
 a globally-unique identifier for that patch.  It propagates